To fix this issue, multiple forums and sites recommended downloading an app called SDFix. The rooting process took several hours and required a system reset afterwards, but it is rooted now. Apps such as Root Checker said that the phone was rooted properly, but the SDFix did not work.
The next step I took was to try to flash an older 4.3 ROM to the phone, as it would still have SD capability. I wiped the cache as well as the Dalvik, but the installation of several roms, both stock and CM, have failed with the error:
Assert failed: getprop("ro.bootloader"? == "l710vpbLj7"...
repeated for about six other file names, which I think are different bootloaders.
Now when I turn the phone on, it looks like it has been reset, but I get the notification "unfortunately, com.google.process.gapps has stopped", which appears again immediately after closing the first one. It is an endless loop and I cannot do anything in the phone. Is there any way you are able to help me?