in case others cannot start their device, this worked for me
https://support.remarkable.com/s/article/Software-recovery - this link works
Recently tried to start my Pro, the screen flashed twice then nothing. Tried again. Same. did the obligatory research, eventually did what others said, use a slow charge overnight. Still Nothing. OK, last resort. followed the link above and its directions, using a USB C cable to my Mac Studio and choosing ARM download for the software. There is an option for intel and for windows download. The directions are very simple, easy to follow.
At first I used the option to reset the device. went thru the entire process, got an error at the end. Try again, this time choosing to restore the device. After the process finished, the device came back to life. It did the reset anyway. had to go thru the initial set up process but I use the device for chess study, write answers from quizzes and puzzles, etc. No big deal for what was lost.
Just wanted to pay it forward in case others need help and have the same issue. Evidently the issue was the battery had no juice, was displaying 0 when the device came to life, now I know to check the battery often. My bad.