Silverado No start issue....truck cranks, starts then shuts off

I sent out the PCM and BCM for programming. I talked to two mechanics and they said they need to see the problem. This is intermittent so when I took it in, the truck was behaving with no issues. I cannot reproduce this issue, the truck picks and chooses when it will have the issue.

The mechanic was able to get the truck started. He found that the fuse box was dirty and full of seeds, like the cover was left off for a long time. The cover has always been on since I've owned the vehicle. He cleaned it out and started checking the fuses/relays. He could not find any issues with them. In the process of pulling out and plugging back in some fuses, the dash gauge warning lights came on and the truck started. They monitored the truck for another four days, but could not reproduce the issue. This is an odd intermittent electrical issue that will probably happen again, but hopefully not.