Did I do something to make my Mac Mini not reboot?

Question

Bad bad news for me. It appears I have a broken Mac Mini, very suddenly.
I decided to upgrade RAM, and decided to take it to the store to have them install it for me.
I shut down my Mac Mini at home. I had an external hard drive attached to it at the time. I think I 'ejected' it on the computer. I forgot to actually physically take it out of the USB port. I remember the computer and/or the hard drive 'complained' when the computer shut down but didn't think anything too much about it (made noises).
I take it carefully in a box to the store and give it to them.
Then, even though I had just used it hours ago, they now say it is broken and cannot be robooted. They say their usual process is to boot it up, then intall the Ram, and there is no point in intalling the RAM now since it is broken. They will take a look at it for $45 to see what is wrong with it. Then call me with further repair costs before doing anything.
I didn't use packing material in the box. I don't beleive it moved an inch though. Could the Mac Mini really be that fragile? I didn't drive far to the store. No sudden stops. Careful in carrying it. They insinuate something could have happened to it as I carried it. I can't believe it would be that fragile though. Like I said, I don't think I moved it barely an inch.
Could it be I shut it down improperly somehow, and this has caused it to completely break?
could it be the external hard drive somehow? Maybe if I take it home and try to attach the hard drive, it will be happy?
It just seems so odd that it broke so suddenly.
Should I pay the $45 for them to check it out, or try taking it home and seeing what I can do with it?
ANY help much apprecaited.

Answer 1

It's an odd thing that the system fails to boot and sticks at the grey screen with no external drive attached, yet you haven't (at least knowingly) installed MacOS on the external. It's possible you dragged something over that you shouldn't have, but that should have resulted in the mini, with no external attached, giving some indication of the failure to boot up, such as the flashing question mark.
It's also possible of course that the act or reconnecting the external and booting the system were coincidental, and that there's really no relationship between the two events!
If it were my system, I'd run Disk Utility (in Applications>Utilities) and see which drive the system is booted from, and use the Verify Disk tool to check for errors on the drive. One thing seems pretty certain however, and that is that even though the system runs fairly slowly, there's nothing much wrong with it in hardware terms, thus aside from new memory, it should not be a major problem to get it running well. Backing up your data to the external and then doing an Erase and Install of MacOS before restoring your data from the backup should be all it takes.
After that, if your external drive is the same size or bigger than the internal, and since you haven't seemed to use it much, you might want to consider using a utility such as Carbon Copy Cloner, or SuperDuper! (I prefer the latter) to do a regular complete backup of your drive, such that if anything goes wrong, not only will you have a backup of your data, but also a full duplicate of the boot drive. That would get you readily back in business is the drive failed or your data was corrupted, and could be automated so you don't have to mess with dragging files yourself.