Uscc 6800 Gps, Custom Roms, Downgrading Guide

[maverick351ci]

ImCokeMan - True, the downgrade is more for getting settings back so you can reupgrade to the GPS rom, or if you was getting rid of your phone, warrenty whatever you may want to, or for the daring like me that will give it a try, if it causes problem you can allways upgrade again!

Tiermann - Thanks i changed the link on the first post, but i kinda figured that the updater would get the most current release.... am i wrong?

[puff]

Originally Posted by ImCoKeMaN

Ok, the radio thing seems to really have people confused and understandably so. I was VERY direct with my warnings for a reason. I am certain that your phone does have some code on it that is from the GPS rom, and that may or may not show itself in roms you use that aren't designed for GPS. The radio section is made up of different parts and the one that shows the radio version number is getting flashed, but the part that loads it isn't going to "revert" to stock as it is write protected (something to do with the 785 nbh header). This can cause issues and it was related to what ended up bricking my device.

Sounds like there's a section of the "radio" that doesnt get updated when the radio is flashed back, perhaps i can best explain with this reference... found an interesting fix for Invalid Vendor ID and Invalid Model ID that actually broke WiFi on the Excalibur -> http://forum.xda-developers.com/showthread.php?t=328690 but the solution -> http://forum.xda-developers.com/show...3&postcount=16 involves a dump and some hex editing to correct those problem sections in NaND memory that could not be overwrote. i could be wrong, but i think that's what ImCoKeMaN is trying to point out. That it IS POSSIBLE to downgrade, however the actual NaND memory section that is "protected" may not get overwrote, may become corrupt, could be wrote to different/mismatching memory addresses, and could cause problems... or you could NEVER notice a problem at all...

Originally Posted by ImCoKeMaN

Of course, if you're crazy like me feel free to make bricks. I could use a new patio.

although i would love to learn more about the whole r0m dump, disecting a r0m, and do some good ol' hex editing.... i never find the time, and believe me.. i've been searching. so if anyone wants to h00k me up

[puff]

you can read more about the downgrading debate here

One Final comment for tonight:

On the Original (not slim) Sony PSP, once you downgrade from an "official" 3.XX release of the firmware back to the kickass 1.5 - you cannot upgrade to any 3.XX "official" version without very high chance of bricking your device. This is due to xtra files left behind in the NAND memory - Although you can install custom firmware so that you have the best features of both 1.5 and 3.XX

Once again, same concept i believe

[ap90033]

Followed this guide and the internet doesnt work. It cant connect. I call us cellular and went through all the steps with them and it cant connect. I think it is the Radio Rom that wont allow it. HELP!!!!!!!

[ap90033]

Originally Posted by colonel

Well, the bricked mode is not just stuck in bootloader. However, I just wanted to make sure you were giving ample warning to people before they jumped into your guide once you put it up. If it works great, but I think people should also know that there are some serious consequences that may occur.

You mention being able to flash back to original US Cell Rom, where do you get it and how?

[ImCoKeMaN]

Um, Trust me its WAY more risky than just normal OS flashing. There is part of the radio that will never be overwritten after going to GPS radios (by current known means) despite the version number actually changing. This can lead to bricks (see sig) but not always immediately. Additionally, there could be some random incompatibilites with an inconsistent radio image.

[Getitnowmarketing]

Originally Posted by ImCoKeMaN

Um, Trust me its WAY more risky than just normal OS flashing. There is part of the radio that will never be overwritten after going to GPS radios (by current known means) despite the version number actually changing. This can lead to bricks (see sig) but not always immediately. Additionally, there could be some random incompatibilites with an inconsistent radio image.

Thanks for the heads up there. I successfully or so I thought took my xv6800 back to stock 2.09 ce and 1.30.60 radio and used it for a week stock with no apparent ill effects after reverting from dcd 3.01 and 3.35 radio. Won't do it again unless I need to FRU it.

[ImCoKeMaN]

Whatever customizations you collected when you did the downgrade should be saved seperately and made available to everyone so that not everyone does the downgrade.

[mykleh35]

Great write up maverick351ci! thanks for taking the time to write it down and of course for the 'big ones" to get where few of us USCC people have gone! On a related subject we are often asked to THANK SOMEONE when they help you... how do you actually do it??? because you get a big THANK YOU from me!!=D>

[justpctech]

Originally Posted by mykleh35

Great write up maverick351ci! thanks for taking the time to write it down and of course for the 'big ones" to get where few of us USCC people have gone! On a related subject we are often asked to THANK SOMEONE when they help you... how do you actually do it??? because you get a big THANK YOU from me!!=D>

this explains how the Thank You system works here> http://forum.ppcgeeks.com/showthread.php?t=23898 , but it boils down to you need 50 posts minimum to use it. then it will show up at the bottom right side of each post.