First I'd re-format the SDCard or try another one to see if that solves the issue.
will get you both serial and partition access.
If you don't have a backup or can't manually solve the problem there are also other ways to restore
After you established a working root again I recommend one of the million ways to resize the data partition
, rather then using APPS2SD. gparted worked very smoothly for me
. Backup your device before!