WhatsApp for OnePlus 9RT

WhatsApp's background sync and auto-backup can keep the CPU and radio busy and add to heat, but it's rarely the only cause. Check Settings > Battery > Battery usage to see which apps are draining the most, then for WhatsApp specifically open Settings > Apps > App management > WhatsApp > Battery and set it to Optimized. Inside WhatsApp, tap Settings > Chats > Chat backup and set Back up to Google Drive to Weekly or Monthly instead of Daily. If heat continues, reboot the phone and uninstall any recent app or beta update, since a misbehaving app or a bad OxygenOS build is a more common cause of sudden drain than WhatsApp alone. See how others solved this on Reddit

This is usually a corrupted cache or an incompatible beta build. Go to Settings > Apps > App management > WhatsApp > Storage usage and tap Clear cache (not Clear data, which deletes local chats), then reboot. If it still force-closes, update WhatsApp from the Play Store so you're on the current stable release. If you joined the beta program, open the Play Store > WhatsApp listing, scroll down and tap Leave under the beta section, then let it update to the stable version. See how others solved this on Reddit

The green vertical line is a known hardware fault on these AMOLED panels, not a WhatsApp or software bug, so a factory reset won't cure it and it normally needs a screen replacement through OnePlus service. Before handing the phone in, protect your chats by opening WhatsApp > Settings > Chats > Chat backup and running a manual Google Drive backup so everything restores cleanly onto the repaired or replacement device. See how others solved this on Reddit

First try a forced restart by holding Power and Volume Up together for about 15-20 seconds, and leave it on a known-good charger for 30 minutes in case it's a deep discharge rather than a dead board. If the phone stays unresponsive, your chats are recoverable only if WhatsApp was backing up to Google Drive. On a replacement Android device, install WhatsApp, sign in with the same phone number and Google account, and it will offer to restore the latest backup during setup. See how others solved this on Reddit

Whether you repair or switch phones, back up everything first while the phone still works. Open WhatsApp > Settings > Chats > Chat backup, choose your Google account, and tap Back up now so chats and media land in Google Drive. For your most important conversations, also open the chat, tap the three-dot menu > More > Export chat as a separate safeguard, since an out-of-warranty hardware failure can make the phone inaccessible before you get a chance to back up later. See how others solved this on Reddit

A restore that stalls near 99% is almost always a weak or interrupted connection to Google Drive. Switch to a stable Wi-Fi network, make sure you're signed into the exact Google account that holds the backup, and leave the phone plugged in and unlocked. If it still hangs, clear the cache for Google Play Services via Settings > Apps > App management > Google Play services > Storage usage > Clear cache, then uninstall and reinstall WhatsApp and let it detect the backup during initial setup rather than skipping and trying later. See how others solved this on Reddit