[SOLVED] [WORKAROUND] SD card not visible when in recovery mode

SOLVED: Found a workaround: I installed TWRP via flashboot command in android SDK from laptop. Now I can see my SDCARD and continue.

Trying to install a ROM on my unlocked original XOOM tablet, but when I go into recovery mode it appears as if it's not mounted.

I've searched around, and I can find no solution.

I tried formatting the SD card and no luck.

I'm trying to follow this guide:

[ROM][4.4.4] OmniROM - Wingray - bigPart | Motorola Xoom | XDA Forums

Is it possible to use adb as a workaround?

I tried to adb sideload the TWRP zip file and the img within it (as the instructions are not clear on that) and I get device not found.

(however the first time I tried to sideload just the zip file I got nothing from the console)

Any help is appreciated.