There are a few things that are odd with your setup. But I will get to that in a bit. The very first thing you need to do before anything else is to make sure that your hard drive is healthy. If you have a drive that is starting to go bad (and it can happen even for relatively new drives), then no amount of software tinkering will ever fix your issues. So, first let's make sure hardware is not an issue.
1. Get HDDScan (it's free; google it) and run it. Check the S.M.A.R.T. attributes of your drive. In particular, pay attention to any yellow warning icons shown on the report. Also, any attribute that has "reallocation" in its name should be checked; make sure that you have no reallocation sectors; and all
raw values shown (even if you see nothing but green icons) are less than the
threshold value. Generally speaking, all drives have a number of extra sectors that can be used to work in place of bad ones. That said, any reallocation sector count that is non-zero might be an indicator that your drive is starting to have issues.
2. If HDDScan basically reports a healthy drive (i.e. no bad sectors, no warning icons, etc.) then the next step is to make sure that your drive is sufficiently powered and plugged into the correct slot (
always use the USB port closest to the edge of the console). Generally speaking, most "thin" drives (2.5inch or sometimes referred to as "laptop" drives) operate at under 500mA (max USB 2.0 power). However, not all of them do. If that is the case (i.e. you can check the datasheet of the drive to see that they are under the 500mA current draw), then these drives can be sufficiently powered by a single USB cable. However, there are 2.5inch drives that actually exceed the 500mA limit, especially those which were not manufactured as an actual external drive (i.e. 2.5inch USB HDDs that come with their own enclosures are likely fine; but if you got your own 2.5inch drive and a separate USB enclosure, then who knows...). Thicker 3.5inch drives must always have external power (AC adapter) because the use both 5V and 12V, whereas USB ports only provide 5V. They also draw much more current than their 2.5inch counterparts. Anyone with a 2.5inch USB HDD and is unsure about their power draw can simply buy a USB Y-cable.
3. Now, assuming a healthy hard drive that is getting sufficient power, the next thing to check is whether the USB by itself is configured properly. This means you should remove the SD card completely. The bare minimum, with respect to soft-modding, that your Wii needs is: a) the Homebrew Channel installed, b) Bootmii installed in boot2 and/or cIOS with the NAND backed up, c) cIOS 249 (base 56, d2x v10 beta52) and cIOS 250 (base 57, d2x v10 beta52).
You have way too many unnecessary cIOS's and the ones you do have are reversed (249/250 using 57/56 base, respectively) Priiloader is nice, and definitely recommended if you do not have boot2 options for Bootmii. But this is all that is needed to get a USB loader app to run (I personally use USB Loader GX). With those requirements in place, format your HDD drive using FAT32 (not exFAT). You can always go back and modify this setup once you get your loader running. DO NOT USE WBFS MANAGER! (WBFS drive format is out of style these days, and it is better to use .wbfs files as opposed to formatting a drive to WBFS format). In fact, for diagnosing issues, you should consider doing everything manually.
i) After formatting your drive, create a folder named: apps
ii) Extract USB Loader GX so that it resides inside this apps folder. You need to take extra care here as most zip files for apps include the directory structure for the apps. The directory structure should be (after extraction):
HDD -> apps -> usbloadergx -> (files pertaining to USB Loader GX)
iii) Create another folder (in the root of the hard drive) named: wbfs
iv) Inside this folder, copy a single game (preferably with the .wbfs extension). As an example,
/wbfs/New Super Mario Bros Wii [SMNE01].wbfs
Notice the game title followed by [game ID] in the file name.
v) Configure USB Loader GX to load this game into its menu, and work on getting just this first game to work (doesn't have to be Super Mario Bros Wii -- I'm just using this as an example)
Avoid using any game/backup manager; this is one less point of failure or cause of problems. As you can see, there are only a few things that could be the cause of our issues at this point: cIOS installation, USB Loader GX (version, and folder locations), the game file (in this case New Super Mario Bros Wii [SMNE01].wbfs), or how our drive was formatted. (This is under the assumption that the drive is healthy, and getting sufficient power, while plugged into the outer USB port.)