2004 GMC Envoy car seems to be dead

Replacing these ignition switch and ignition lock will cause a dead battery and no start problems. The small gear on the ignition switch must be in the proper position or alignment with the ignition lock cylinder if it isn't the switch will remain on when you have removed the ignition key an will not rotate the ignition switch to the proper position to tell the engine to start.
Make sure the alignment of the ignition switch gear is correct. If not turn gear with small flat head screw driver until is stops. On the ignition cylinder housing use a screwdriver to rotate the lock cylinder housing gear counter clockwise until it hits a stop then connect the connector to the ignition switch. Install ignition switch into the lock cylinder housing. Use a screwdriver to rotate the lock cylinder housing gear clockwise to start position- allowing it to spring return into the run position. Align the lock cylinder and install the lock cylinder into the lock cylinder housing. Then reinstall else in reverse order of disassembly.
Start here after a charged battery assuming the battery is still good.
Let me know if this answers your question or if you have any more questions.
Talk to you soon, TY

There is a circuit that goes through the ignition switch that when ignition switch is turned on unlocks the shifter. Assuming ignition switch is installed correctly and being a electric locking device the battery must be in good condition to function properly.

That's good news, progress has been made. The transmission gear sounds to me like the shifter cable is out of adjustment reflecting a different gear on the instrument cluster when the shifter in drive. The vehicle's computer sends data to the instrument cluster on which position the gear shifter is in and if the cable is out of adjustment it will put the transmission in a different gear than anticipated. Check the shifter cable.
The service engine light and other warning light can not be reset by disconnecting the battery as we could with older vehicles. Some codes will need to be reset by using a scan tool. Most auto part suppliers will do this for free. If the warning lamps stay on please send the fault code retrieved to me and I find where to start diagnosis on why the lights are on.

There is a switch on the driver side of the auto transmission that relays which gear the transmission is in to the vehicle's computer the computer then sends the data to the instrument cluster in which gear has been selected. My first impression would be an out of adjustment on the shifter cable to the switch mentioned above.
Try to move the shifter with the shifter button pressed slowly to try and get the instrument cluster to read shifter is in drive. This will show you if your switch is in fact working and that the cable is out of adjustment. If you can see drive selected as you slowly move the shifter then you'll need to adjust the shifter cable at the shifter side or where the cable connects to the transmission side. Good luck
Let me know if this answers your question or if you have any more questions.
Talk to you soon, TY

I've found a Technical service bulletin published by the manufacture that mirrors what you've just said. I need some more information from you. First look in the glove box. See if there is a sticker with a bunch of three digit codes (XXX). Specifically I'm looking for codes: m30, m32, m33, mt1, mn8. Next do you have an aftermarket alarm system and/or remote starter?
Try having all the codes you just gave me reset by the same place you got them from. These codes could just be from the dead battery your vehicle had. Reset and see if the codes return.

Ok, good. It sounds to me all these codes are a result of the dead battery slowly depleting due to the ignition switch issue. The TSB (technical service bulletin) refers to all of the codes you listed as "loss of voltage to the transmission solenoid power circuit". Which means the dead battery or now a circuit problem. My bet is the dead battery. Have all the codes reset and see if any codes return. Then we know there is still an issue. Hope this helps, talk to you soon. TY