You will lose your data, but that can be gained back if you: A: Backup with iTunes | see here B: Backup with iCloud | see here Plug your phone into a Mac/PC with iTunes. Power off your phone Press and hold the sleep/wake button and the home button simultaneously for 10 seconds Release the sleep/wake button, but keep holding the home button for about 5 seconds iTunes will say “detected an iPhone in recovery mode” click “Restore”. To regain your data from iCloud after the restore click here To regain your data from iTunes after the restore click here
Follow these steps from verizon.com. I think you should clear the cache, then uninstall and reinstall WhatsApp. (1) From a Home screen, swipe up or down from the center of the display to access the apps screen. These instructions only apply to Standard mode and the default Home screen layout. (1) Navigate: Settings > Apps. (2) Locate then select the appropriate app. If system apps aren't visible, tap the Menu icon (upper-right) > Show system apps. (1) Tap Storage. (2) Tap Clear cache (bottom-right).
This was in the comments, but it should be an answer… This is not my words, they are from Augustine. I am not trying to steal the answer, but help the person who asked. “Hi No Name, of course before heading those power boards, turn the power off. There maybe some charge in the capacitors, just take some caution to discharge the charge and yea, safety PPE like gloves is recommended.”