My nokia 6233 batteries become useless after charging for sometime

If the rechargeable battery is more than 3 - 4 years old then the battery could be worn out. Rechargeable batteries have a finite number of charge and discharge cycles and will lose their charge capacity over time, i.e. won't charge to 100% and gradually the charge reduces until the battery won't charge up at all.
OR The battery shows a 100% charge but when the adapter is disconnected the battery drops off to zero capacity in a very short time.
If the battery drops to an unacceptable charge level then the battery needs to be replaced.

The power (On/Off) button is not responding probably because it is broken, the phone is dead, or the battery is dead or drained. Connect the phone to a charger and check whether the phone charges the battery or not. The power button is indeed not responding and broken when the phone charges the battery. The only way to turn on the phone is by replacing the power switch.

When the phone doesn't charge the battery, the phone may be dead or the battery is dead/drained. To revive the battery and verify whether the phone is dead or not, check it here.

hiiii plzz tight the screws of your phone may be this will help you
if it doesnt work then there is some hardware problem in your cell

hiiiiii dear this may be a solution that make back up of data & format the cell

pls help me how to format 6233

you should change your battery

Maybe ur phone battery is down. Charge the battery through another's phone and try to install firmware again.
If ur phone is still not detected by comp. maybe boot data of phone is corrupt
Then the last option is to replace hardware.

Only battery problem friend. Change battery.

No, take the battery out and bring it to an auto part store and they can test it.

it could be a display problem but firstly u must try to update its software from nokia care