How can I get shell access on my almost dead phone
if you can go in recovery mode, you can also go in download mode.
if you use odin, i guess you have a samsung device.
Normally push togheter power button, home button, volume - button
turn any samsung mobile in donwload mode.
downlaod an official ROM from http://www.sammobile.com/firmwares/
and flash it with odin.