This is my first post on the forum, wishing it could be under better circumstances

First issue (sort of): I was having trouble starting from cold (-5 to -25 celcius) while unplugged. Obviously, this is no big surprise, but this is where my real problems started. I had one no start when I left my Deli outside my work for 6 or 7 hours in the cold unplugged. I cranked it for awhile, but after a couple minutes the batteries gave out and the starter started to slow down. With a boost however, she fired right back up, no problem!
Second issue: This happened again when I forgot to plug it in (this time around -10 in my garage), and again, with a boost she started right up!

Third issue (the bad one): Again, outside my office. Forgot to plug her in, for 7 hours or so in -30 (BIG MISTAKE). She cranked for a couple minutes, and then died (starter slowing down dramatically). I tried boosting her, but it was no use. With cables hooked up for a couple minutes, she would crank slowly for 10-15 seconds and then die. The next day I tried again, with the block heater plugged in (again in -20): had her hooked up for at least 20 minutes and she cranked for a while, then died, the same as before. I tried a couple more times in succession, but each time she cranked a few times slowly, getting slower each time: no more normal-speed cranking. The case was the same when I tried again the next day (-15). I still have the block heater plugged in, and am waiting for a warmer day to perform the recovery, although what I suspect is TOTALLY drained batteries (not sure if they're the original Japanese batteries or not), no longer accepting a boost (from what I've read on the site).
My plan right now is to head there tomorrow (+8 in Regina, SK

What do you guys think? I've done a tonne of reading and I think I have a good place to start, but any advice is welcome! I'll keep you posted!
