When I had simialr problem, I successfully made this with NO STORED DATA LOSS:   1) Disconnect all the drives 2) Run the jun's loader as reinstall 3) Find device by find.synology.com or Assistant - there were no drives in the system. 4) Leave browser's Synology page opened, do not shut down device. 5) Plug disks back in (no matter, if the machine supports hotswap or not) 6) After a few minutes repeatedly refresh Synology's page (see step 4) 7) After succesfuly loaded installat