I want to propose a theory that could very well be incorrect and that I'm sure will be flamed to death but.....I think it may be related to the bootloaders.
My phone obviously came with 2.2, with the original 2.2 bootloaders. I had the random shutdown issue, it would just turn off completely, sometimes even while I was typing. I flashed rom after rom, no fix.
I finally used the i897 ucckk4 odin one click CONTAINS bootloaders odin package. This is obviously a master wipe and reset to 2.3.5 for your phone, but it will flash the absolute latest bootloaders. There is an odin package with JUST 2,3 bootloaders, however they are not the latest 2.3.5 bootloaders. There is a lot of talk of how horribly dangerous it is to flash bootloaders, but the package mentioned above obviously contains both primary and secondary bootloaders, no matter what is on your phone right now, as long as you use a reliable USB cable on a reliable computer when flashing the above package, you will be perfectly fine.
Using that one click will give you the latest BL's with a stock 2.3.5 rom. I then use Odin to flash a corn 2.3.5 kernel which gives you CWM. Then I use CWM to flash whatever rom I want, and now my phone is absolutely up to date.
After I flashed that package with the latest bootloaders, the shutdowns are absolutely gone - as in through the three rom's I've been messing with since flashing the 2.3.5 BL's, I haven't had a single shutdown. Before flashing BL's I tried every rom and kernel for the captivate I could find, but staying on 2.2 BL's, and the shutdown continued. Tried master wipes and one clicks, no difference. Try the one click mentioned above! Obviously you will have to reinstall your rom. if you're thinking you can find the one click with JUST the bootloaders so you don't have to reinstall your rom - don't bother, in every instance for me, upgrading bootloaders will confuse your rom and it will bootloop.
In my case, upgrading bootloaders made my shutdown issue disappear, but of course it could be an isolated case. My girlfriend also has a captivate, and she has the batch of captivates that will not let you access download mode. She has the random shutdowns so bad that it's driving her mad and she's ready to get an iPhone with her upgrade. I have read that the batch of phones with an inaccessible download mode is actually a slightly corrupt secondary bootloader. This leads me to believe even further that there is a link between bootloaders and stability/shutdown issues.
I have a USB jig on the way to get her phone into download mode, then I will flash the latest bootloaders, then probably a jellybean rom. I will report back if this fixes her shutdowns as well
Sorry for the lengthy post! Just wanted to share my findings
My phone obviously came with 2.2, with the original 2.2 bootloaders. I had the random shutdown issue, it would just turn off completely, sometimes even while I was typing. I flashed rom after rom, no fix.
I finally used the i897 ucckk4 odin one click CONTAINS bootloaders odin package. This is obviously a master wipe and reset to 2.3.5 for your phone, but it will flash the absolute latest bootloaders. There is an odin package with JUST 2,3 bootloaders, however they are not the latest 2.3.5 bootloaders. There is a lot of talk of how horribly dangerous it is to flash bootloaders, but the package mentioned above obviously contains both primary and secondary bootloaders, no matter what is on your phone right now, as long as you use a reliable USB cable on a reliable computer when flashing the above package, you will be perfectly fine.
Using that one click will give you the latest BL's with a stock 2.3.5 rom. I then use Odin to flash a corn 2.3.5 kernel which gives you CWM. Then I use CWM to flash whatever rom I want, and now my phone is absolutely up to date.
After I flashed that package with the latest bootloaders, the shutdowns are absolutely gone - as in through the three rom's I've been messing with since flashing the 2.3.5 BL's, I haven't had a single shutdown. Before flashing BL's I tried every rom and kernel for the captivate I could find, but staying on 2.2 BL's, and the shutdown continued. Tried master wipes and one clicks, no difference. Try the one click mentioned above! Obviously you will have to reinstall your rom. if you're thinking you can find the one click with JUST the bootloaders so you don't have to reinstall your rom - don't bother, in every instance for me, upgrading bootloaders will confuse your rom and it will bootloop.
In my case, upgrading bootloaders made my shutdown issue disappear, but of course it could be an isolated case. My girlfriend also has a captivate, and she has the batch of captivates that will not let you access download mode. She has the random shutdowns so bad that it's driving her mad and she's ready to get an iPhone with her upgrade. I have read that the batch of phones with an inaccessible download mode is actually a slightly corrupt secondary bootloader. This leads me to believe even further that there is a link between bootloaders and stability/shutdown issues.
I have a USB jig on the way to get her phone into download mode, then I will flash the latest bootloaders, then probably a jellybean rom. I will report back if this fixes her shutdowns as well
Sorry for the lengthy post! Just wanted to share my findings