2001 S80 T6 Temporary failure to start

[j+shammock]

We purchased this 2001 S80 T6 with 131k about 3 months ago and found no noticeable mechanical problems at that time, but it didn't take long for that to change. The lights in the cluster that indicate odometer reading and any other useful info have been too dim for daytime reading from the beginning. There has been an orange triangle lit that apparently goes with the SRS airbag service urgent message, that we can read in evening, also from the beginning. We have been told of a laundry list of issues with some of them being remedied by some of the others. The most noticeable was the slipping transmission, which we opted to replace with a used one. We immediately found that the used one was worse than the original. (Forgive me for being long-winded, I want to be as detailed as possible.) We then chose to have the original rebuilt since mechanic said the issue with it was a selanoid and some of the clutches and this would give us a 2 year warranty. But the mechanic informed us that although the work was finished that the transmission worked fine as long as we don't run the a/c. He stated that we would need to see a dealer to address this issue. Obviously very disgusted, we decided to drive it without the air until we could recover from the financial blow. The drive home proved that not running the air made no difference, this newly rebuilt transmission slips, period! It doesn't end there though. In the less than two weeks since we brought it home it has failed to start two times. Does not crank, lights, radio all that works. It doesn't seem to be connected to extended driving, actually has no degree of predictability. Could any of our issues be connected? Can anybody suggest a plan of action or give us ideas about how financially painful this might turn out to be? Really would appreciate any help at all. Thanks