I have a el gli last night we pulled into a driveway turned off motor and interior lights wouldn't work the smartlock light was flashing very dimmly and there was a ticking sound coming from under the dash It had now power to start headlights etc so I took off battery lead and gave it 5 mins then it restarted .could this be a ecu fault or bcm .........Last week i has to replace inhibitor and tps switch due to a auto fault was going well to then and yes i reset everything after thanks chas

sounded like a bcm fault. did you happen to still have the headlights and other accessories on? because once my ef fairmont made a terrible noise under the dash when i had the headlights still on and the stereo, i had to disconnect the battery, it was fine after that

yep radio gps on charge thats it

You took off the lead? - where the battery leads on nice and tight - that also causes that symptom

yep they were
allways carry a 10 mm spanner

well going to replace both battery leads etc they are probaly overdue we have done 300 000 kms in car not sure how old they are