The dreaded first gen T6 GM trans issues

United States
What I Drive
2004 Volvo XC90 T6 AWD
Hello all! I'm new to the forum and the proud new owner of a 2004 XC90 T6 AWD with the problem prone GM 4t65e trans. I picked up the vehicle for $550 with known trans slip so I'm not really complaining. The engine runs like a top with 166k miles on it, good brakes, good tires, and so so interior and exterior. So first things first I changed the fluid and filter, meaning I drained the 8 quarts from the pan, didn't drain the other 4 or so from the torque converter, refilled with fresh and no change at all. She won't shift out of 1st gear, even tried forcing it to change by shifting manually but to no avail. It also shutters when taking off from a stop, like the torque converter or clutches are slipping. Old fluid was completely destroyed,smelled horribly burnt and the magnet in the pan was covered badly in metal particles, nothing big just micro particles. No loud clicking, whirring or other noises from trans, just doesn't shift and slips from a stop. So my question is this, does it should like a problem that a master rebuild kit would fix? Or should I be looking at a new torque converter and/or new shift solenoids also? Maybe even speed sensor or valve body? If it just needs to be rebuilt it's no big deal, I can do that myself, but no sense in rebuilding if its a bad torque converter. Any help in pointing me in the right direction as to what I should replace or rebuild first would be greatly appreciated. Thanks!