Dual wall toilet flush

Turn off the water supply to the toilet first. Then open the lid and check if the flush button or cable is stuck, and make sure the rubber seal/washer inside is sitting flat and clean. If that does not fix it, the flush valve or button likely needs replacing.

It may be the spring needs replacing or the internal flushing unit there isn't much cost to either and an easy fix

Turn off the water to the toilet first using the small isolation valve on the pipe feeding the cistern (turn the slot 90° so it’s across the pipe), or use the main stop tap if there isn’t one; then remove the lid/button (usually unscrews or gently pops up) and check the dual-flush button’s plastic rods/clips haven’t come loose or been adjusted too long (which can stop the button moving and hold the valve slightly open); if the water is still running, the usual cause is a dirty/worn flush valve seal—twist/lift the flush valve out, clean off limescale and refit, replacing the rubber seal if it’s perished; if it’s overfilling, adjust the float/fill valve so the water level sits below the overflow (or replace the fill valve if it won’t shut off); if you’re renting and can’t stop it quickly, leave the water isolated and report it.

turn off the water and clean the moving parts

?1. Stop the Running Water IMMEDIATELY
?Before attempting any fix, you must stop the water to prevent waste and potential overflow.
?Turn off the Isolation Valve: Locate the small valve (usually a chrome knob or screwdriver slot) on the water pipe coming out of the wall or floor and leading into the cistern (the tank behind the toilet). Turn this valve clockwise firmly to shut off the water supply.
?Alternative: If you can't find or turn the valve, take the lid off the cistern and hold the float mechanism up (it looks like a cup or an arm) to manually stop the water from filling.
?2. Address the Button/Mechanism Issue
?The button not pressing is usually due to the button mechanism being improperly seated or broken.
?Remove the Cistern Lid: Carefully lift the lid off the tank.
?Check the Button Rods/Cables:
?Rod Type: The buttons usually push down on two plastic or metal rods. Check if a rod has become disconnected, snapped, or is jammed by something inside the tank.
?Cable Type: Some modern flushes use cables. Check if a cable has kinked or become detached from the main flush valve underneath.
?Re-seat the Mechanism: If the button assembly is a twist-lock style attached to the lid, ensure it's properly twisted and seated. Sometimes, simply taking it out and putting it back in fixes the jam.
?Check for Obstruction: Look for anything blocking the plastic rods or cables from moving freely.
?3. Address the Continuous Running Water
?If the water is running, the Flush Valve (the main component at the bottom center of the cistern that the button operates) is likely stuck open.
?Jiggle the Mechanism: Gently push down and wiggle the top of the central column (the flush valve) inside the cistern. Often, a stuck seal will drop back into place.
?Inspect the Seal/Gasket: The rubber seal (flapper or donut gasket) at the base of the flush valve may be dirty, perished, or misaligned.
?Cleaning: With the water off, remove the central column (it usually twists off or has clips) and inspect the rubber seal for debris (like limescale or grit) and clean it gently.
?Replacement: If the seal is cracked or clearly damaged, it needs to be replaced. You'll need the model number of the toilet or flush valve mechanism to buy the correct part.

First, turn off the water supply to the toilet. Then, lift the tank lid to check for debris or limescale on the flush valve seal, or a stuck button mechanism, and clean it

Depends, you can do a temporary fix until you call a professional. Initially you need to cut off the water supply by locating small tap or screw valve on the pipe going to the toilet, turning it clockwise to shut off the water. Next lid off the top of the toilet tank, then can test it by pressing the flush button manually from inside. Is it stuck or lose? You can then attempt to align the button rods with the flush valve below so they move freely. If the seal looks worn, it may need replacing.

Hi,
It looks like your push button has broken, so this would need replacing

First, try jiggling the buttons to see if you can dislodge anything. If that doesn't work, you might need to remove the toilet tank lid and inspect the flush mechanism. Look for any broken or misaligned parts. Sometimes, you can adjust the chain or the flapper to fix the issue.

Is it an old toilet? Sounds like either a poor fitting or worn washer unit. In my limited experience, the latter. If you're hands on you could photograph the unit in the cistern and take it to a plumbers merchant to find the same/similar part.

Not 100% without looking at it.

If your dual flush toilet button is jammed or the water keeps running, the issue likely lies within the flush mechanism or the fill valve. First, check the flush valve seal for leaks or wear. If the button feels stuck, try jiggling the handle or inspecting the connection between the button and the flush valve. If the water continues to run even after the flush, a faulty fill valve could be the culprit.

Carefully take off the lid of the toilet cistern to access the flushing mechanism.Check if the flush button is stuck or jammed.

Sometimes debris, mineral buildup, or worn-out parts can cause the button to stick and not depress properly.See if the flush valve or the mechanism connected to the button is stuck in the open position, which would cause water to keep running.

Make sure the button’s rods or cables (if any) aren’t broken or disconnected.Press or move the flush mechanism manually to see if the water stops running when the valve closes.Turn Off the Water Supply Temporarily
To stop water from running and prevent wastage, turn off the water supply valve behind or near the toiletIf the flush button is broken or the mechanism is jammed, you may need to clean, adjust, or replace parts.

Sometimes, replacing the flush button assembly or the entire flush valve kit is necessary.

Switch off the water, try to fix the button first time if is stuck, if is damaged replace it.

The filler inside the system might just be stuck on the side try moving it a little bit to see if it releases

There's a isolation valve behind toilet get screwdriver and turn slowly to stop water or lift back o toilet up and check to see if it's a sticky button.

Turn off water at isolation valve on supply pipe to toilet or isolate supply at main stop tap

If you can’t press the button on your dual-flush toilet and the water keeps running, it’s likely due to a problem with the flush valve, button mechanism, or seal inside the cistern