TeraStation Live NAS (HS-DHTGLBE4) Full, No Longer Accessible

[DalangAsli2]

I'm hoping someone can point me in the right direction. I have an older TeraStation Live (HS-DHTGLBE4) NAS, which has been working perfectly up to now. I was moving files to the NAS from a PC.  An error appeared on the PC stating that there was no space left on the NAS to copy the remaining files. I was able to log on to the web interface of the NAS, but there were no errors showing - only that all 4 drives were at 100% capacity. I did not realize at the time that this was as big a problem as it has turned out to be. I logged off the NAS, but was unable to log back on. NAS Navigator 2 can no longer find the NAS. My Windows shares say the connection is already in use and I cannot see the NAS at all. I cannot telnet to the NAS. I can only ping it. No errors are showing on the display screen of the NAS - the only light blinking is the green activity light. I have not attempted to reboot the NAS since this happened. Searching the forums has not turned up any problems related to a full NAS.
        Is there any way for me to get back on to the NAS in order to delete some files and then hopefully be able to connect to it to move files off of it and make space available?