4) After reading several threads here and on the DIYElectricCars forum, I thought that upgrading to a 64GB was ideal, and that we should leave 32GB unpartitioned. Turns out I may have misunderstood some of those threads, as the 64GB chip was only suggested for MCU2 and newer. So Tedsk and I decided on a 16GB chip instead for my first gen MCU, leaving 8GB unpartitioned. Thanks
@verygreen for input here.
Background: a few months ago the MCU (on my 2015 S) went black for the first time, Tesla did the double firmware reinstall and it worked again for some weeks. But it went black again so emmc replacement was inevitable.
So yesterday my friend (who has a phone repair shop and does frequent bga work) volunteered to help me replace the emmc chip. I got the 64GB Swissbit (like mentioned
here).
We tested the mcu (without lcd) on a bench setup/psu before the removal of the Hynix emmc and it worked fine, we could ping the MCU ip and ssh into it (was already rooted).
Chip removal went smooth, as was the reading&writing of the old&new chip (RT809h programmer). We dit not modify the image in any way, since it was already rooted and booting to a certain degree.
New Swissbit chip placement went smooth, so we were very hopeful that it would be a succes. But no cigar sadly, the MCU would not boot
.
At first attempt the power pulled was oscillating between 6 and 10 Watts (reboot loop?), we tried to reflow: still the same. Then we removed the Swissbit chip, put it in the programmer, and luckily it read just fine and verified 1:1 with the dump we had.
Then we tried to reball the chip but that was an ordeal. My friend only had a general .5mm stencil instead of a specific bga153 grid. Took a lot of time to clean things up.
Anyway we ran out of time and flowed it on the pcb and bench tested again: Now it pulled 10W constantly now, but still it wouldn't boot. We ordered the 153 stencil so we can reball properly. Will try that in a few days when package arrives.
We assumed the failure was because of the sloppy reball job, but now I'm reading your post I am starting to doubt if I purchased the wrong emmc chip?
I hope someone (
@verygreen ?) can comment?
Also: is there any way (like leds or serial) to see on what stage the boot of the MCU fails?