WhatsApp for OnePlus X

On the OnePlus X's OxygenOS, the usual cause is WhatsApp staying awake in the background to sync media and keep its connection alive. Open Settings > Battery > Battery optimization, find WhatsApp and set it to Optimized so it can sleep when idle, then inside WhatsApp tap Settings > Storage and data and turn off Media auto-download on mobile data. Reboot, then check Settings > Battery > Battery usage after a day to confirm WhatsApp has settled down. See how others solved this on Reddit

WhatsApp's official iPhone-to-Android transfer needs both phones connected with a USB-C to Lightning cable and the OnePlus X freshly set up (or factory reset). During the OxygenOS setup wizard choose to move data from iPhone, install and open WhatsApp, verify your number, and when prompted scan the QR code shown on the Android screen with the iPhone, then keep both phones unlocked and plugged in until it finishes. iCloud backups can't be restored directly into Android, so this cable method is the only supported way to bring chats and media over. See how others solved this on Reddit

Newer Android versions moved WhatsApp media into an app-specific folder, so the WhatsApp Images folder can stop appearing in Gallery even though the files still exist. Open Files by Google or any file manager and browse to Internal storage > Android > media > com.whatsapp > WhatsApp > Media > WhatsApp Images to confirm they're there, then copy that folder into your Pictures or DCIM directory so Gallery re-indexes them. If they're genuinely gone, reinstall WhatsApp and restore from your Google Drive backup when prompted during setup. See how others solved this on Reddit

WhatsApp uses its own basic in-app camera that doesn't tap into OxygenOS's full camera processing, so photos taken inside a chat look soft and washed out. For good quality, shoot with the stock OnePlus Camera app, then send the photo from the chat using the attach (paperclip) > Gallery option. To stop WhatsApp from compressing it on send, attach the image as a Document instead of as a Photo. See how others solved this on Reddit

Some warmth is normal, since a video call runs the camera, screen, radio and encoder at the same time, which is one of the heaviest loads for the phone. To reduce it, take off any thick case during long calls, use Wi-Fi instead of mobile data where possible, and lower screen brightness. If it gets uncomfortably hot rather than just warm, reboot and check the Play Store for a pending WhatsApp update, since an outdated version can sometimes cause a runaway process. See how others solved this on Reddit

Restore only works when the new phone uses the exact same phone number and the same Google account that holds the backup, so first add that Google account to the OnePlus X via Settings > Accounts. Then install WhatsApp, verify your number, and when prompted choose Restore from Google Drive. If it stalls, confirm the backup actually exists at WhatsApp > Settings > Chats > Chat backup on the old phone, and make sure both phones are on Wi-Fi with enough free storage. See how others solved this on Reddit