Tab 3 Bricked or fixable?

After getting my first GSx phone, I didn't use my Tab 3 for a rather long time, but recently decided I wanted to use it again as I had no other tablet. However, I'd forgotten that it had run into a problem:

The middle of the screen has the "android robot", with message "Downloading... do not turn off", but in the top left, I see this:

Could not do normal boot.
ddi : mmc_read failed
ODIN MODE
PRODUCT NAME: SM-T217S
CURRENT BINARY: Samsung Official
SYSTEM STATUS: Custom
KNOX KERNEL LOCK: 0x0
KNOX WARRANTY VOID: 0x0
CSB-CONFIG-LSB: 0x30
BOOTLOADER RP SWREV: 3
WRITE PROTECTION: Enable

I'm a career long techie, but not with android OS, and I haven't had a lot of luck learning if this is a "brickable" issue or if there is a fix. I'm perfectly willing to set it back to factory (do NOT need root) if that's what it takes, and set it all up again, but don't know if that's an option. Problem is I don't know if this is a hardware issue or software or both. That said, I have a second, identical Tab 3, which is showing the exact same issue, so I'm guessing it's probably/hopefully not hardware.

I have done some research, but what I've seen is to run it in ODIN mode and flash it, apparently back to factory. I've tried the Home/Power/Vol UP hard reset method, but it just comes back to the same screen. I did learn that I can download the ODIN software (not sure which version works with my old Tab3) and install/run it from my laptop while the Tab3 is cabled to it, which makes sense, and while I understand what flashing is, I'm guessing that's part of the ODIN process too. Keeping in mind it will not go beyond this error screen, is there a guide on how to do all of this, assuming it's not hardware? I don't know for sure if the battery can be pulled as I've done with some of my earlier Galaxy Sx phones when they ran into issues--dunno what the "white" covering on the Tab3 is that the guides mention, other than some kind of "dust screen". Hate to remove it if it serves that purpose and isn't truly removable, but...

Here's a quick and dirty web page I created showing exactly what I see, which appears to be common, if this helps. It's just 2 images:

www.packwebs.net/tab3problem.asp

Appreciate any help!

elaine