Problem: Synology Rackstation (or Diskstation) reboots endlessly. Power LED blinks, ALERT LED blinks. Some drive LEDs green, most are red (or orange). One drive LED might blink indicating drive activity. LAN connection LEDs are dark (inactive). No access.
Solution: Try powering it off, pulling all drives, peripherals and RAM, and rebooting. (Don't forget any USB peripherals, like a UPS.)
If the Power/ALERT light behavior persists, and it doesn't return to a solid-on Power light in about a minute - your Rackstation is dead.
Or, at least, it took Synology support chat < 60 seconds to conclude mine was dead. Maybe you will be more fortunate.
Synology would not confirm in my case, but I can't help but think the dreaded Intel C2000 bug could cause this.
BAD NEWS: Unless your unit is in warranty, or covered under the Atom +1 year extended warranty, you are SOL.
GOOD NEWS: Your data is most likely OK! You can (carefully!) plug the drives in to a new NAS and all your stuff should still be intact.