Hi Paul,
I am using a Nexus S with android 2.3.4.
2 Days back the device powered down due to low battery and I have not been able to boot it since then.
Whenever I try to switch it on I get the vibration and Google logo for 1 second then the screen blanks and returns to the Google logo with the back, menu, search and home keys lit. Hvae not been able to go beyond that after a thousand battery pulls and reboots.

I have tried using recovery mode, on selecting apply update from /sdcard i get the following error message:
E: failed to mount /sdcard (No such file or directory)
Have tried wipe data/factory reset and wipe cache partition, though they execute, they have not solved my problem.

I am the end of my patience and would appreciate any help you can give.
Almost threw my phone today, need help urgently.