just go to the 2nd post of
Scottys noob friendly root guide-start to finish and follow the directions starting at
method #2)"full ruu" method to unroot 
when launching the recovery,make sure the image name in the
fastboot boot command matches the exact name of the image in your miniadb_vigor folder.
recovery-ra-vigor-3.14-gnm.img is given as an example,but your recovery may be named slightly different.
the generalized command is:
fastboot boot exactrecoveryname.img
also,make sure the recovery youre trying to launch is an .img,and not a .zip file