I did replace both the battery and USB board.
No loss of data since it's a "dead" memory (like an HDD) which doesn't need power to retain data. Or else, it would be lost when powering off the phone.
The main problem I had is after the repair, the flip camera is defective. When it flips, it stutters after fully flipping. Then the camera app shows an error message saying it can't flip. If I tap out of the pop up error message, the camera module remains flipped, but the image is upside down.
The workaround I found is using another camera app for selfies. I can dismiss the error message without getting the image upside down. Open camera works fine for instance.
I very rarely take selfies so I don't really care.
I thought the problem was because I didn't stick properly the backplate around the flip module. But I put sticky tape all around, as it was originally made, but got the same result.
I didn't have to touch to the camera module for the repair. So I don't understand what's going on. 🤨
Another small problem I had is that the speaker sound quality worsen. I guess that's because the speaker is against the USB board. I might have failed to put it back correctly. But I was really careful. So I can't tell what's wrong.
Most of the time I use earbuds or external Bluetooth speaker anyway. So that's not a big deal. And the speaker sound is still usable.
I was scared to break the back panel. But heating it for several minutes, and taking time to slide the spluger underneath, little by little is key to succeed. That was actually the easy part for me.
The hardest was putting back the fingerprint reader. There's a ribbon going through a hole in the fingerprint "board" (actually a thin plastic plate). You have to unplug this ribbon to completely remove the backplate and work considerably. Plugging it back while positioning the fingerprint stuff was very hard for me somehow. But I made it.
Finally, one of the pin plug at the right bottom corner of the phone can be tricky to attach back. Its wire is a bit short. And positioning the pin just fine if challenging.
I'm still glad I made the fix though. The USB port was almost dead. I had to push on the side of the USBC plug to counteract the contact loss and get it to charge. So I had to change it.
The battery was draining super fast. So I also had to change it.
The other solution was just buy a new expensive phone.
I don't really like the last Zenfone. Too small, no flipping camera... 😕
And my Zenfone 6 is still doing fine. It's fast enough. It works fine. I don't like to spend money when it's not really necessary. And don't want to generate unnecessary e-garbage since I'm concerned about environment preservation and slave labor in precious metals mines. So even though I don't wanna go live out of the society, I want at least reduce my impact as much as I'm able to.
Sac that Asus don't seen spare parts themselves.
Good luck with your repair!