You have a problem with a stuck hard drive. That length of time dormant its not unusual. You do have some of the partitions visible which is a start. First thing to do is switch her on and boot to that screen and leave the computer on all day long. I once had a ViperCD on a 500 that took over a day and then magically OK. I have a 4000 sitting behind me here that can take all morning before the light clears and I can start using her. These drives are slow to respond.
Also at what angle were you storing the drive... vertical, upside down. Try standing it on its side and opposite to how she was stored and maybe giving the box a very gentle tap. I have had A2000s that I literally stood on end and left them running all day. I would suggest the old freezer trick which I have used to revive half a dozen stuck drives. Mostly I just tap them. Listen when she boots and see if she make a couple of high pitched noises.
You will like this ...
https://www.scuzzscink.com/amiga/scuzzblog_september19/scuzzblogdseptember19_2201.htmI recently had the red light of death on a PS3 that I used a hair dryer to revive, but that was a slightly differing problem.
Little tip, if you do get her working try switching her on every now and then. I have an A600 on the bench at the moment that has a slowly dying hard drive. Happens.
PS I also have a Checkmate with an external SCSI drive that leaves the screen blank for ages and the light stays on. I have to soft boot CTRL right and left Amiga at least three or four times before she shows me an error message that identifies a checksum, which I cancel and then remarkably the drive activates. I have another 600 that I have to boot hard and then twice from a soft but she always fires up. There is a trick to it. Doesn't always work but with a little TLC should be able to get her back. All is not lost.
I have a similar drive to yours.. not the same but another make. It has a drive connector at the back.
https://www.scuzzscink.com/amiga/scuzzblog_december18/scuzzblogddecember18_2602.htmscuzz