This iPhone 6 was water damaged, after recover, it stucks on searching ….  for cellular service , dail *#06# gives no IMEI number

Enter DFU mode and restore via iTunes gives unknown error -1 and then stuck on iTunes recovery mode.

This suggests something wrong with baseband

 

It is good practice to reball baseband chip as well

Pads on logic board are cleaned.

 

Prepare the chips, shiny shining solder balls….

Update (29/06/16)

Replaced ICs in above picture and still no baseband.

Replaced again, still no luck.

Two capacitors directly goes to baseband CPU are grounded when baseband CPU is installed, but everything is fine when it is uninstalled.

Let’s make sure by measuring voltage drop on the chip, these pins are shorted. Yes, I am Chinese.

This conclude baseband CPU is faulty, bad news…  Apple did it in a way that you cannot just change baseband chip, it has to go with your hard drive, CPU and your finger print reader (touch id)

Wait, How did the baseband cpu die in the first place?

This phone was water damaged, baseband power IC was faulty and it is possible baseband chip was damaged by this.

Ok, I know the problem , can we just replace the above mentioned things, easy, right?

hrm… not really. the CPU has 2 layers and very easily bent(damaged) when take it off, and it won’t last, I don’t do this kind repair.

Wait! what do you mean it is 2 layers and why don’t you do it?

here you go, iphone 6 CPU,  been there, done that, not again.