All Lights on Dashboard Led Up and No Safety Features Working

I had this issue a month and a half ago where all my dash light led up while I
was parked idle. Vehicle was drivable but none of the safety functions were
working including the cruise control. I took it to the deanship next day and
they returned it after keeping it for a day saying it was just a software issue
fixed under warranty all good. Two days ago same thing happened again. I
took it in today and now dear is saying they will replace the spark plugs, fuel
injector and adjust the valves. Now first two are covered under warranty and
valve adjustment is not covered under warranty and will cost $225. But this
might not fix the problem and could be a beginning of a series of fixes. What
should I do? I read other similar question and there could be many things
that people have faced and tried including battery change etc. It is been
maintained at the dear with all scheduled service up to date and has 50K
KM's.