Website Trade In with Custom ROM?


Apr 30, 2023
Hey all, I bought a marble 512GB Mi 11 Ultra from Trading Shenzhen. I opted for them to flash it for me, so I have stable TWRP. My current software version is V13.0.13.0.SKACNXM.

I've never plugged the device into a computer, haven't got the first clue on how to flash or update (scared to do anything since I always read stories of phones bricking).

Anyway as you all probably already know Xiaomi have an excellent deal with the 13T Pro so I'm going to buy it through them, but they have a trade in offer. They are offering me £338 + £50 extra to trade my Mi 11 Ultra in. I have two questions I'm hoping someone can answer for me please:

1 - Do I have to do anything before sending it to them? The website says they'll completely wipe the phone and re-install the software. I am going to manually take my data off anyway, but do I need to plug the phone in and ensure it's on another ROM or anything like that? Or will it be fine since they're going to do all that anyway?

2 - Am I better off selling myself instead of trading it in? I understand it's a pretty decent phone, special edition marble version of the 512GB. Excellent condition etc. If I can make a couple hundred more then I'll sell it privately; only issue is I lose the security of knowing the company would wipe the phone clean for me, and if I don't do it correctly the other person on the receiving end may be able to retrieve my data? Or they might brick the phone themselves and then come back and blame the seller?

Any assistance would be much appreciated! Thank you very much