Hard Reset to Factory Settings without USB access

I've got an Asus ZenPad 300C that is crashing constantly. Things I have tried: - Clearing cache. I am unable to access Settings to clear the cache but was able to run a clean-up app, which I think did some of that. No effect. - Factory Reset. If I use Power+Volume Up to access recovery mode I can see the options - FASTBOOT MODE and POWER OFF, but the power button doesn't work so there's no way to actually select FASTBOOT MODE. I tried connecting via USB to run ADB and do it that way but USB Debug mode is not enabled and I cannot get into Settings on the phone to allow it because Settings crashes. - Battery. I have removed the back and temporarily disconnected the battery but that made no difference. Is there any other way to perform a hard reset or troubleshoot and fix this issue or is it done for?