[MUGDHA BHUSARI]

Power button gets pressed twice for the screen to start again on a light touch. If the phone goes off it takes many tries to put it on

[B. Diddy]

Welcome to Android Central! Can you clarify the problem with the power button? I don't quite understand what you're trying to describe. Does the phone not realize that you're trying to press and hold it?

If the power button doesn't work correctly, you won't be able to wipe the cache partition. You'll probably have to get the power button fixed first.

[p3ntyne]

Power button gets pressed twice for the screen to start again on a light touch. If the phone goes off it takes many tries to put it on

You mention that it takes many tries to turn the phone back on, so technically, it should be possible to turn the phone on while holding volume down (on whatever key it is on your device). Have you tried that? If then, it would be too hard to get into the recovery, you could keep it in bootloader mode and reinstall the OS from factory images, which would erase the cache anyway.