Transmission Control Unit, how to change it out?

Can you recommend a step-by-step instruction video or written explanation telling how to switch out the old with the "new"(used)? Do I need to remove the battery cable first to save the codes? Also, I can't find a mechanic near me (Lower Queen Anne). Can you refer me to one? Lastly, is it safe to drive it to the shop?
Thankfully, Miriam

Thank you so much for the step-by-step instructions to replace the TCM. As soon as the rain lets up, I give it a try.
God bless you! Miriam

Hi, again. As you know, I am not a mechanic, however, I am determined to fix what I can fix. To wit, I followed your instructions and discovered that 1) There is an insulated cable on top of the unit. Additionally, the bolt that needs to be removed from the right side of the bracket is unreachable. I assume that someone else needs to be removed to get at it. You can only see it on a cell phone. There is a yellow collapsible tube running to the back seat. Probably not necessary to remove, right?
I am so close, unhooked the battery cable, wore the wrist strap, bought the silicone grease, got the wiring harnesses off and now what? Do I need to remove something else in order to get at the bolt securing the TCM? I really appreciate your help!
70 yr. Old grandma Miriam. P.S. It sucks to be old and poor.

Here are photos of the transmission unit and bracket with the bolt on the right bracket. It looks like the unit has to slide up vertically but there is an insulated cable above the unit and it is secured tight in the bracket.

Hi again. Got the two bolts on the right side but can only lift the unit off the bracket on the right side. Can't see any bolts on the left side. The black insulated hose is tight on that side. Also, tried to pull it straight out towards the accelerator pedal but it has to be lifted off the right back remaining bolt. Only the nut came off. Could you send me a pic of any clips that may be holding it in on the left side? I really appreciate your assistance.

Sorry, don't know if these will help. The unit seems to be dislodged, but couldn't lift the left side up enough to move it out, towards the accelerator pedal. I felt around the left side, and it felt like there is a bolt in the front. Could that be holding the unit to the left. Bracket?

I finally got the nut off the front left bracket of the TCU. Couldn't get it out of the driver's side so removed the panel off the passenger side. Then I pushed the unit towards the pass. Side and was able to jiggle it out from that side. Hurrah! Now, how do I get it off the brackets?

Sent three pics. I can't slide them out, even using a large screwdriver. Do I need to try to find brackets for the replacement unit?

Yes, I used a thinner screwdriver, and the bracket flew across the room. Installed the "newer" TCU from the passenger side. Couldn't get the front bolt to line up, so I wiggled the unit and it was immoveable. Forgot to use the silicon on the plugs, but they went in easily. The ck. Engine light wasn't on and no clunking sounds when I took it for a test drive! Should I disconnect the three plugs and put the silicon on or not? Tomorrow, I'll test it again with the Autel diagnostic tester.
Thanks for all your help; I feel ok driving again.
Miriam

I asked if I needed to grease the three wiring harnesses that I plugged into the TCU, not the the spark plug boots. Wanted to know if it's necessary before putting the trim back on.

And, do I spread a small amount of the dielectric grease on the male plugs?