Tune wont cause short or fry ecu
if you can talk to ecu with ecutek cable then ecu is functioning.
If for example to flash an incorrect ecu calibration to the ecu it can cause car not to start . for exanple if you flash an auto transmission calibration to a manual car it wont start. But all you need to do is flash correct ecu calibration to car and your good.
If however if you flash a pre faclift calibration to a post facelift car or the other way round it does cause an ecu \imobilisier lockout ( i know cause ive done it ) to get out of that one you need to flash in the correct ecu calibration and then loop pins 4 to 13 on the obd port for over 30 minutes with ignition on.
see my post on swapping ECU
https://www.ft86club.com/forums/showthread.php?t=102810
Tell me the year and if car is auto or manual and also what ecu calibration id is currently in car like ZA1JB01C ?
Also if you ever flashed a different ecu calid to car ? than what it was stock, i know tune is different but was ecu calid changed ?