build.prop
I had the same problem with my Build.prop file, on my Vibrant 3g. I know its not a Droid but i stumbled upon your post so i hope i can help.
I followed a website to edit my Build.prop so i could get netflix to work on my Vibrant 3g. I edited the build.prop using ES File Manager and saved an original file in the sdcard, then rebooted.
Long story short I ended up with a bricked phone that would splash VIBRANT then black out and vibrate randomly. I called it a android seizures.
I could only get into Recovery mode at this point so I looked into editing a update.zip file so I could insert a working unedited working Build.prop file just to get my phone back and save my data, I found this to be very difficult, whether finding the right Build.prop file settings and creating working update.zip
Hours later... What worked for me was downloading ODIN software and putting my phone into Download MODE. (i had no idea there was another mode other then Recovery Mode for android at the time) Odin software then found my device on my PC and I was able to get a new/old android firmware file off xda that worked with my phone and overwrote my phones corrupted firmware. Then BAM working custom Firmware saves the day.
Downside:
I lost all my data but I'm unbricked, I looked into lots of alternatives even recovery mode ALL USER DATA DELETE did nothing. So I opted to lose everything just to get my phone to work. It was quick and dirty.
Another hope if you can do it:
There was another method i read that someone got ADB (android device bridge SDK) to work even though they could only access Recovery Mode as well.
This was beyond my skills as ADB didn't seem to work on my PC, it was probably a driver issue on my end. But they mentioned they were able to get to there build.prop and edit it. Some how they mounted their phone and ADB'd into their system. If anyone knows how to get ADB to connect with a ANDROID phone that hangs at boot please post how you did it. I'm curious...videos even better. =)
Ill leave links of what i used. Good Luck everyone, and DO NOT edit your BUILD.PROP file unless you have a recovery solution other then rebooting ur phone and wishing for the best.
I hope this helps someone out there.
LINKS I USED to learn what i did.
Youtube:
[video=youtube;AnY7P14JSWQ]http://www.youtube.com/watch?v=AnY7P14JSWQ]YouTube - Flashing Firmware with Odin on Samsung Vibrant‏[/video]
(shows you how to get ODIN and put a Vibrant into Download mode)
Thanks ZDoomCentral from youtube!
Odin Link Download for PC
Odin:
Multiupload.com - upload your files to multiple file hosting sites!
xda site where i found a new firmware for my vibrant. Just search XDA for Droid Firmware and for sure you'll get something. OR Droid users will probably help you get a new custom firmware here as well or link you.
[ROM] T959UVJI6 OTA Stock ODIN Flashable - xda-developers
Link to Firmware i used for my vibrant 3g
MEGAUPLOAD - The leading online storage and file delivery service
Link to ADB SDK
Android SDK | Android Developers