Help please, PTT button switches off radio

Hi, help please? I have Binatone Terrain 650 2 way radios which have worked fine until today. One is working as it should but the other is switching itself off when I hold in the PTT button to transmit.
Manual is no help, has anyone had this problem, all settings are the same on both radios.
Any ideas gratefully received, I have removed the battery pack & replaced it but still switching off.

Switch battery packs from one radio to the other. If a pack is defective and doesn’t hold a charge anymore, the action of pushing the PTT will drain it instantly and it will shut down.

Otherwise, they are $20 radios and it is not worth even having someone looking at them to see what’s wrong. It is not likely to be worth fixing.

It is most likely a bad battery pack. The average lifespan of a rechargeable battery is between one to three years. If you’ve had the radios for awhile or you recharge the batteries a lot, it may be time to replace the rechargeables.

Thanks for the suggestions, I’ll try the swap first although the bad handset still shows full battery after switch off.