How can I be certain that my transmission has went out and not a computer proble on 2001 Ford Escape

I took my car to a transmission shop and had a diagnostics ran and they say the transmission is shot. How can I be sure that it is not a computer problem? Another transmission is going to be anywhere from $1400 to $2900 I am told. Is this reasonable? I am really screwed here since this is me and my daughter only vehicle and I have no family to help. I just dont know what to do.....please any advise would be appreciate.

Asked by for the 2001 Ford Escape
Yea,I already to it for a diagnostic. That is why they say it is shot.
1 more answer
did you have to tow it in? Are there multiple squares around multiple gears? does it drive at all or idk not leave 1st gear? if any of those things apply you may simply have a bad trans range sensor. $1400- $2900 is absurd btw, I'd go on ebay or go to a junkyard keeping in mind you can source a transmission for your car from a mazda tribute or mercury mariner as well for probably about $100-$150. Then you've got to find a mechanic who isn't a dickhead and will actually install it for you since there are lots of places that will tell you they won't because it's from a junkyard or ebay and they didn't get to charge you extra $ on top of their parts cost. Secret truth in auto mechanics- they don't make their money on labor, they make their profit by charging 2X to 3x and beyond on parts.