mobile

So, I'm having a big problem with my S4 at the moment. After having some problems with several apps, being that I couldn't properly open, restore, or uninstall them (I think it has to do with Foldermount), I decided to format my external SD card, and perform a factory reset. Everything seemed like it was working well, and when it rebooted and asked if I wanted to repair root access, I said 'yes' (not sure if that has anything to do with the issue). Then, after some time, it went on with the boot up. However, it was stuck at the samsung logo. So, I tried to go into download mode, like people were suggesting. I held down UP volume, and the power button, but all this does for me is turn off the device. I can't seem to get into recovery mode to perform another reset, and I can't even get into download mode. Also, when I try to turn off my phone using the power button, while it's in the seemingly infinite boot up, it instantly turns back on. The only way I can turn it off is by removing the battery. So, any help would be greatly appreciated, I have no idea what to do. Thanks in advance