I have same/similar problem. I used EasyMer yesterday. First I installed boot menu and after that Mer. Unfortunately, when Mer was being downloaded by Mer install, I forgot the whole thing (for hours ) and when I remembered to check the process, the battery was empty and my N810 was off. Battery was quite full so I think the installation finished.

When I loaded the battery and started my tablet, I can get to boot menu by pressing the menu button. If I selected Mer from menu, it starts to load it from external memory card but after a short while, screen goes black and N810 reboots.

I tried to redo the installation process but it didn't help. If you try to start Mer without the external card inserted, the result is exactly the same. Boot menu --> starting from external card --> black screen --> reboot.

Any advice for Linux & tablet n00b?