Dangers of downgrading after installing GPS radio (and a little on signing)

[ImCoKeMaN]

Ok there is a TON of confusion here, let my try to clear things up.

SPLs: (3 color screen which if you see this you are not bricked!)
0.40 will be overwritten by a flash if an nbh includes an SPL
2.31 will not be overwritten by an nbh (only via OS aka unlocker 0.40)

Radios:
1.xx radios/non-GPS work with 0.40 SPL only
3.xx radios/GPS work with 2.31 only

OS has to match the SPL/Radio as well, but less danger in that section just stuck in SPL

SPLs/Radios/OS are all device specific, do not just repackage nbh files with a vogue ID. There is a modelID embedded for a reason.

CID of radios is less important physically to your device, but you are still running a risk if your carrier does not offer the radio since your warranty will be voided.

Now to clarify my statements on reverting back after GPS:
Short answer: Don't do it!!!!

Details (nobody likes to listen to me saying not to, but here's why I say it):
The 1.xx radios are loaded with a normal nbh header and they can be overwritten by a different radio with no problems.

The 3.xx radios are loaded with a 785 nbh header which is only compatible with the 2.xx SPLs and at least some portions of the radio itself will not be overwritten when reflashed.

The radio actually is what loads the SPL so this is where the compatibility comes into play. When you have the new GPS radio and flash back to a non GPS radio the portion of the radio that loads the SPL does not get overwritten even though the version on the screen will revert to the 1.xx. This isn't always a huge deal when using the 2.xx SPL, because the loaders are compatible still (unless it actually did get overwritten). Once you go back from there to a stock SPL though you very well could get a brick in download mode.

This may not happen all the time there could be different circumstances etc, but i have bricked a few devices and this is what i've come up with.


PS: Also there seems to be confusion about what is actually a "signed" rom i might do a write up on that, but basically if it was dumped or customized (created with dutty or nbhgen) its not signed, if it was at one point on an HTC site as is than it's signed (the ones I call Carrier EXEs).