what do you recommend to downgrade to 3.55 to get your dump files and the upgrade to 4.21 rebug and then switch to dex. know any good tutorials?
I'm recommending you to pay close attention to what you doing. The video that you've posted is out of date cause nowadays you can skip the Factory Service Mode and use the Rogero Auto Patcher to skip FSM. FSM is accomplished by using a USB dongle or PSP app.
And also the video does not tell you to double-check your BIOS back up. The step that has all switches down but the third UP on the TF coverboard. Which backs/dumps your BIOS onto the MICRO SD card. ALways Always check your dumps. If you don't and you continue then U might end up with a paper weight.
You must login or register to view this content.. And you don't have to downgrade to get your dump. GET IT BEFORE you start flashing shit.
Really up to you where you wanna end up, either 3.55cfw or 4.41cfw or 4.46cfw. You decide!!!
And for going CEX>

EX, I've seen tutorials but I would really look into it before you advance.