The docs of the OBD2 shield state : Use it with caution if you are sure your total power will stay under 150mA. (I guess I should interpret this as making sure the setup should not surpass 150mA ?)
I'm trying to figure out what went wrong
A quick back-of-the-envelope suggests that operating at increase the voltage rating from 6.3 to 10v would decrease the expected FIT (failures in time) by over 100-fold (134/1.05 = ~127).
Which (to me) actually suggests how _safe_ tants are (when used appropriately, of course!)
BTW, 2200uF is a big value cap. What role does ot play in the circuit, just out of interest?