well one mechanic simply plugged his device to the battery and checked its voltage but did nothing more. it was on the low end of the green from what I saw. So how does the low voltage explain the ASR light and limp mode if I may ask for my own knowledge?

I was also told that I shouldnt charge the battery via jumper cables to another car when my battery dies because it messes the computer ABS/ASR system in some way. I did not know that and did it anyways when my battery died a few weeks ago so this could be an additional factor to consider?