'92 535i attempted to start and failed

[Abond1]

I drove my 535i to drop off my grandson at school this morning then went to pick up my other grandson. I parked and shut off the car and left it for about 45 minutes while getting my grandson ready. When I went to crank the car, it attempted to turn over but stopped. I tried a second time and got nothing. No interior lights, no dash lights, nothing. What could the issue be? I am very new to the BMW world and have no clue where to start.

[dlindenmayer]

I would be checking the connections at the battery pretty quick. Sounds like a loose cable