I used laptopscreen.com.

Use a purpose built heating pad at 100 degree Celsius eg; https://www.aliexpress.com/item/Uyue-948...

I used a purpose built heating device at 100 degree celsius. Lower temperatures didn't work.

I would suggest getting the cable loose first as the vibrator comes out suddenly and you could break off the cable if it is still glued down.

And the answer is in here. It sits at 8.9 then ramps up when it is happy with everything. http://www.righto.com/2013/06/teardown-a...

Why is it 6.8 V and not 16V?

Why wouldn't we check the voltage here instead of later?

While reassembling it's easier to insert the cable into the connector while placing the SIM board into place. This allows you to get the end of the cable back enough and slip it into the connector.