ok so i got this phone last year from somone on craigslist i think he had the phone rooted already with a custom rom not sure how all that works but anyways ill give you some more info one what i currently got going on with my phone (side note: yes it is update.zip and not update.zip.zip)

okkkkk so i am running

android version: 2.2
baseband version:
kernal version: android-build@apa26 #1

build number: frf50

and when i boot into bootloader and as i am trying to select recovery something quickly shows up about passimg.img not found or sumthing like that

and when i get into the recover menu (build : RA-nexus-v1.7.0) i dont see anything that says "update phone" i go to flash zip from sd card i get

E: no signiture (391 files)
E: verification failed

if i need to provide any other information let me know! i really wanna put 2.3.3 on my phone ive tried resetting my phone to factory setting also and that didnt help eitheri know that i cannot put the update on some rooted version or the phone or sumthing like that is there any way i can reverse that?

any help will be greatly apriciated sorry for any messed up spelling also.