maybe the volume button is stuck, when it crashed try put pinset/clip to the side of the volume button and pulled it up on both ends if not working ->open your casing with screw ->check the volume button position hope it can help you
try to clear app cache and app data ->setting ->apps manager ->clear app chace and app data or try to reinstall the apps if cannot resolve your prolem, reset your device to factory setting
check the rubber button and analog, maybe it just dirty ->open casing with screw ->release the battery ->open PCB board ->clean the rubber button and analog with chemical cleaner hope it can resolve your problem
maybe your aftermarket battery not good ->check the voltage of battery with voltage meter ->and compare the both battery ->if different, so the aftermarket battery isnt good
first i think, you sholud check the driver wifi in device manager control panel -> system and security ->device manager try to update your wifi driver device manager->right click->update driver or download driver package in device support website