Sorry If this thread is old, but I thought, that it should be know, that you can only do this up to 3.55 firmware , and after that or if its easier, you have to change the BGA chip, and seems the same question keeps being brought up lately, heres the thread I started, and was succesfull
Only reason I replied is to help those searching to do this also sorry if I bumped the thread.
but its for a good reason .
https://www.acidmods.com/forum/index.php/topic,39158.0.html