In the event you think your stock ROM is faulty, or you want to flash back to a previous version on your Samsung device, here is how. This is for Samsung devices, and a general guide at that. Some carriers may have more detailed steps that need to be taken. I cannot guarantee how well this will work for every device. The things you will need: - Download and install ODIN - A program called 7Zip - A copy of your stock ROM in question. Odin is a program that can utilize the MD5 file to install ROMs to your device. MD5 files can be anything from recoveries, modems, and even ROMs. First, one of the things that may need to be done is to update your device drivers. You can do this one of two ways. -You can search the net for your updated drivers. Download and then install to your PC. -Or you can download or update Kies. Part of those processes are to install or update drivers. Once drivers are installed, a restart of your PC may be required. In fact, I would highly suggest it. Second, is downloading and installing 7Zip. 7Zip is a file extraction program, that unzips compressed files. Windows has a file compression and decompression program as well. Depending on where you get your file from, having both is handy in case one works and the other does not. Third, Your copy of your stock ROM. This will be the compressed file you downloaded. You will need to extract it. The best thing to do is create a file on your desktop. This will make the extracted file easier to find. Once created, you can right click on the downloaded file and click Extract. Either program will ask where to extract to. Click on the small box with the 3 dots and navigate to your desktop and locate your newly created file. Next, you will need to download and install ODIN. Once done, you should start it by right clicking and 'Open as Administrator'. This option works best for using ODIN in general. This is ODIN just after the program has been launched. The MD5 file would go into the PDA box. Sounds weird, I agree, but the PDA box will be your best friend. You don't need to worry about any other Boxes. This is the PDA box that will be needed to flash any file. Once the file is in the box, you would now need to turn off your device, and reboot into Download Mode by holding volume Down and power (If using the Galaxy S3 and 4, Home will also have to be held). This is the first step to getting to Download Mode. This is what Download Mode actually looks like. Once in Download Mode, you can plug in your device. You will need to wait several minutes, as ODIN, your PC, and the device all talk to each other. After some time has passed, upward of several minutes, you should see a box that is colored and has a type, and a number: Ex: 'COM:6' That means your PC recognizes the device and everything should be ready to go. The number is irrelevant. Note the COM:3, and the MD5 file in the PDA box. Now, to begin, just click Start. At this point, DO NOT remove your device until ODIN says finished, or if something goes wrong, it will say failed. ODIN flashing has begun. When ODIN is done, you should see a box that will say reset or passed (depending on which version you have, you may see either or both.). At this point it is ok to remove your device. ODIN fishing up it's process. Testing the reset. ODIN has completed the flash, and by now, the device should be going through the reboot screen. Any problems, try these few things: Update Drivers, and restart your PC; Different cables; Different USB ports. Other solutions may include re downloading the file.