I have a problem with the factory's Maemo system, and I prefer to diagnose and solve it than reflashing as in MS/Windows.

This kind of pocket computers need to have USB OTG and option to boot from an external mass storage device, as in a PC. By this way, oneself can prepare a bootable USB stick, mount N900 partitions see boot logs, find&solve the problem.

If you are under warranty, I suggest you to go to the shop and told them "my N900 turn off due low battery and ......"
May be you can bring your N900 to live but It will hard job and you will need luck.
sorry for the offtopic

I don't want to replace the device (I have data and configurations in it).
I want to access and solve the configuration/software problem as with a Linux PC.