99 Ford F-150 front brake job leads to transmission failure?

A number of things will cause brakes to not release but two things will show up right after a normal brake job. The main one is crud and corrosion buildup in the calipers. That occurs over time but doesn't cause a problem until new pads are installed. To make room for them, the pistons have to be pressed back into the housings, and they're shoved over that crud. When the brakes are applied, the square-cut seal inside bends a little, then when they're released, the seal straightens out and pulls the pistons in a little to release the brake pressure. The corrosion makes the pistons stick and not release. Usually one caliper sticks more and leads to pulling to one side.

The other problem that comes on suddenly is brake fluid contamination. Engine oil, transmission fluid, and power steering fluid will cause the lip seals to swell inside the master cylinder and prevent the brake fluid from releasing. That takes about a week to show up. Evidence of contamination is the bladder seal under the reservoir cap will be ballooned up and mushy. When the brakes lock up, crack open the steel lines at the master cylinder. If a little brake fluid spurts out and the brakes release, suspect contaminated fluid. That's a REAL expensive repair because the only proper repair is to replace every component that has rubber parts inside, and to flush and dry the steel lines.

The rubber flex hoses can tear inside and develop a flap that acts like a check valve. That can happen when the mechanic allows the calipers to hang by the hoses. That doesn't happen all the time but it's one of the things mechanics have to be aware of. If a hose is acting like a check valve, the brakes won't release when you open the lines at the master cylinder but they will release when you open the bleeder screws.

What you're describing sure sounds like contaminated brake fluid.

Don't have an answer for the transmission problem. The dashed lights in the odometer display and the flashing lights suggests an electrical problem. That will also result in shifting problems if it's a computer-controlled transmission. The cause is often nothing more than a blown fuse. If they needed to leave the ignition switch on for testing anything else and ran the battery low, putting a battery charger on it will sometimes cause fuses to blow from the current surge when there's no other problem.

It is entirely possible it's a coincidence that there was a transmission problem that was about to show up on its own and it just happened to be at the dealership when it happened, but given the multiple problems all of a sudden, my guess would be mistakes were made. The typical response at the very nice family-owned Chrysler dealership I worked at would be to start with a free loaner vehicle, then they would obviously take care of anything that was their fault.

The dealer can legitimately ask you to pay for things that break on your vehicle while it's in their possession but proving it wasn't their fault is hard to do, and since they know they're in for an argument they may already have a plan to help cover the cost. Another problem is the multiple people involved. The mechanic knows he didn't cause the problem. His service adviser has to trust his mechanics to not lie and to do quality work, and the service manager has to weigh both sides of the argument and determine if the shop should cover the repairs for free. The first thought always is all three people want to save money for the business, but sharp employees, especially managers, understand that keeping customers happy is the best advertising. They can't automatically fix things without an argument because it will look like they're admitting fault.

Many shops will take care of things that pop up that weren't their fault but they'll almost always contact you first. They're hoping to hear, "oh, it was doing that off and on before". Even if they still fix it for free, the service manager is going to be relieved to know his mechanic wasn't at fault.

Those are just some observations. I've had things occur while I was test driving a customer's car, and I've been blamed for things that weren't working as soon as I got in the car. Some people think if they complain loud enough they'll get something fixed for free. That's the other thing service managers have to think about.

I know this doesn't help with your truck. I can only hope the dealer makes it right. Their goal should be to keep you as a satisfied customer.