I've had Amiga get stuck on the white screen when the kickstart roms have come loose, that is one thing worth checking to make sure they are properly seated.

To see if it is the accelerator try to get them to run the system without it connected to rule it out. In fact it is best to get them to strip the system down and test introducing one new item at a time. First try removing just the accelerator and HDD and seeing if the system will post to the insert floppy screen.