If your OnePlus Open is completely black and won't respond, the first thing to try is a force restart. Just press and hold the Power button for about 10 seconds until you feel a vibration or see the OnePlus logo appear on the screen. This simple reboot can clear up temporary software glitches that cause the phone to freeze.
It's a good starting point before moving on to other fixes.
Check Your Charger and Cable
Your phone might have a completely dead battery. Connect it to the included 67W SUPERVOOC charger and cable, and let it charge for at least 15-20 minutes. The fast charging on this model can bring it back from empty surprisingly quickly.
If you don't see a charging indicator or LED light, try a different USB-C cable and wall adapter. Sometimes the issue is with the accessories, not the phone itself. Make sure the charging port on your Open is clean and free of any lint or debris that could block the connection.
Boot Into Safe Mode
If the phone turns on but gets stuck on the logo or in a loop, a recently installed app could be the culprit. Booting into Safe Mode temporarily disables all third-party apps. To do this, press and hold the Power button until the power off menu appears.
Then, tap and hold the "Power off" option on your screen. A prompt will ask if you want to reboot to Safe Mode. Tap "OK". If your phone starts up normally in this mode, you'll know a downloaded app is causing the problem. You can then restart normally and begin uninstalling recent apps one by one.
Perform a Cache Partition Wipe
Corrupted system cache files can prevent a proper boot. You can clear them without deleting your personal data. First, power off your OnePlus Open completely. Then, press and hold the Volume Down and Power buttons together until the device vibrates and the recovery mode menu appears.
Use the volume buttons to navigate to "Wipe data and cache" and select it with the power button. On the next screen, choose "Wipe cache" and confirm. Once it's done, select "Reboot" to restart your phone normally. This process can resolve boot issues caused by outdated or conflicting cache data.
Try Charging Without the Case
Some phone cases, especially thicker or misaligned ones, can prevent the charging cable from seating fully into the USB-C port. I've seen this happen more often than you'd think. Remove your Open from its case and plug it in directly to see if the charging indicator appears.
Also, inspect the inner screen's crease and the hinge area. While the hinge is durable, accumulated dust or a small piece of debris caught in the mechanism could, in rare cases, interfere with a sensor that manages power states. Gently cleaning the hinge with compressed air might help.
Check for Physical or Water Damage
The OnePlus Open's folding design means there are more moving parts than a typical phone. Carefully examine the inner display for any new cracks, especially along the crease, or signs of punctures. Damage to the inner screen can sometimes cause power issues.
Look for any signs of liquid exposure, which could damage internal components. If you suspect physical or water damage, stop trying to turn it on repeatedly, as this could cause further harm to the motherboard or battery.
Use OnePlus's MSM Download Tool (Advanced)
For a severely corrupted software state that prevents even recovery mode from loading, OnePlus provides a deep restoration tool often called the MSM Download Tool. This requires a Windows PC and will completely reinstall the device's firmware.
This process is more technical. You'll need to download the correct tool and firmware package for the OnePlus Open from official community sources, put the phone into EDL (Emergency Download) mode, and connect it to your computer. Since this erases all data, it's a last-resort software fix before considering hardware.
Consider a Factory Reset
If all else fails and you can access the recovery menu, a factory reset is the final step. Warning, this will erase all apps, settings, and personal files from your device's internal storage. In recovery mode, navigate to "Wipe data and cache" and then select "Erase everything".
Confirm your choice and allow the process to complete. Afterwards, select "Reboot". If the phone was failing due to a deep-rooted software error, this should allow it to boot up fresh. If the phone still shows no signs of life after a factory reset, the issue is likely hardware-related.