Well I followed Multifinder17's advice and managed to make a System 6.0.3 boot disk. The good news is that my Classic's ram is 4MB! the bad thing is that the classic won't boot from Rom or floppy with the HD connected to the SCSI port.
I still have to change the battery just to be sure, but it seems more and more that the culprit is the hard disk. I'll be keeping an eye on ebay for some old SCSI hard disks that would work with the Classic. Though, I do kinda wonder what is the largest hard disk size that it can accept (in MB). The current one is the standard 40MB model, but i've found a ton of 40, 80, 480MB SCSI hard drives on say in Germany (through ebay). But they're not verified to work or have a possibility to return them if they don't.
I still have to change the battery just to be sure, but it seems more and more that the culprit is the hard disk. I'll be keeping an eye on ebay for some old SCSI hard disks that would work with the Classic. Though, I do kinda wonder what is the largest hard disk size that it can accept (in MB). The current one is the standard 40MB model, but i've found a ton of 40, 80, 480MB SCSI hard drives on say in Germany (through ebay). But they're not verified to work or have a possibility to return them if they don't.