That's a soft brick, for the reasons below:
- Handset is still powering on
- adb is responding
- handset recognizes usb cable plugged in (how else were you able to adb?)
- handset recognizes the sdcard
Look at this question to see Izzy's answer on what is classified as a "brick".
Something went awry there and it clobbered the recovery environment... mind giving a bit more details...?
From the comments below, it transpires that the OP pushed over the shell binary file
sh from the root of the phone, (either overwriting it and or/had incorrect permissions) and ended up with a "locked-out" of executing shell commands and fail.
By the way, there is no way to set the permission as the
sh interpreter does not have the appropriate permission for executable bit! So executing any commands on that will fail.
The only remedy is to re-flash the recovery image directly onto the recovery partition, by going into fastboot mode on the handset, usually Power+Volume up, armed with a fastboot binary that must be entered on either the Linux's terminal or Windows's cmd, i.e. two operating system environments, choose one of your own preference:
sudo fastboot flash recovery recovery.img
fastboot-win flash recovery recovery.img
That will restore the recovery environment and then the shell interpreter should work from within
adb shell session next time recovery gets booted into.