iPad air error 40 short PPVCC_main

Hello Everyone,

I have here 2 ipad air that give error 40 after NAND replace. Somehow it is NOT the NAND I found out now. (i was thinking this first because i change the serial number with IPBOX)

But i have a short on PPVCC_main. Could this be occured by the U2 ic (on ipad air it is the U6000)

Because if i check the pad files. None of this lines is going to this ic except the C6091. (but the R6091 is not there so no connection)

Before i am going to remove the U6000 is wanna have some advice if someone else has an idea?

Also i removed the U7000 to check if this was the problem but was saidly not.

PS. i didnt overheated the board because i use 240 degrees celcius on my hot air gun.