Why will my Merc Mount 5.0 AWD not shift into gear?

what means roll?
what means no go.? dead engine or dead transmission.

if the 4wd gear shift (5 pos?) is in NEutral
the engine needs to be shut off or cannot shift out of N to 2H or 4wd. or it grinds 4wd box gears.
key off shift to 2H see if car now drives ok.

if need 4wd say so, and say if on ICE or pavement or?
or if car has 5 Position shifter that means
The Selec-Trac transfer case provides 5 mode positions. BINGO
Selec-Trac is true full time 4wd, near AWD quality.
the dash even shows the lamp FULL TIME or part time.
nice.

I can not understand your post
please tell all things the car does good and bad
not just bad. and tell what roll mean to you.

this is a non uSA car, and this is a USA forum, so we must dig deep to find out what any Escudo has options wise.

gear 3, does that mean car is stick shift, or auto,
we need to know, what you have, exactly , in the drive line.
even the engine helps.
but this is Part time 4wd, right, 2004 was first awd on this car.
so its PT tranfer case, part time 4 wheel drive.
problem 2 is your failed to say what tires are rolling on.
pavement
ice
dirt.
this car is not to be run on pavement in 4wd unless covered with ice.
the operators guide is clear on that, read that yet?

or this.

http://www.fixkick.com/part-time-test.html

click stop driving on ice free pavement there , see the damage.

go off road now and post what it does wrong now, if any thing.
if the 5sp box fails to shift the shift tip plastics are gone.
$5 fix. ask.

Follow these steps:
1. Pull up the brake
2. There is a shift lock release switch available under your gear cover - remove it by using a screwdriver
3. Put the screwdriver in the shift-lock release switch and press on it
4. Now you can change the gear from park to neutral
5. You would need to buy a new cover

Drive it slowly to a reputable transmission shop. There is nothing you can fix yourself.

I have a similar problem. Did you figure yours out? I think it might be the pump in the trans.

Transmission shop time. Don't trust it by driving, could leave you stranded.

Shifting to NEUTRAL
To shift the transfer case to NEUTRAL, first make sure
the vehicle is parked so that it will not roll:
1. Set the parking brake.
2. Start the vehicle.
3. Connect the vehicle to the towing vehicle.
4. Put the transmission in NEUTRAL (N) or have
the clutch pedal pressed for vehicles with
manual transmission.
5. Shift the transfer case to 2HI.
6. Simultaneously press and hold the 2HI and
4LO buttons for 10 seconds. The red NEUTRAL
light will come on when the transfer case shift to
NEUTRAL is complete.
7. Shift the transmission to REVERSE (R) for one
second, then shift the transmission to DRIVE (D)
for one second or FIRST (1) for vehicles with
manual transmission.
8. Turn the ignition to OFF.
9. Place the transmission shift lever in PARK (P) or
FIRST (1) for vehicles with manual transmission.
10. Release the parking brake prior to towing.

************************

Shifting Out of NEUTRAL
To shift out of NEUTRAL:
1. Set the parking brake and apply the regular
brake pedal.
2. Start the vehicle with the transmission in PARK (P)
or FIRST (1) for vehicles with manual transmission.
3. Press the button for the desired transfer case position
(2HI, 4HI, AUTO 4WD or 4LO).
4. Put the transmission in NEUTRAL (N) or press the
clutch pedal for vehicles with manual transmission.
5. Shift the transmission lever to the desired position.
After the transfer case has shifted out of NEUTRAL,
the red light will go out.
6. A re-engagement sound is normal when shifting out
of NEUTRAL.

it could be a few things bent shifting fork or first gear is out reverse runs off an idler that is conected to first gear.

howdy,you need a clutch..thats for sure,101%

shift linkage needs adjusting,,could be bent, easy fix, located along firewall to fram beneath the column, ask your son wut he ran over and didnt tell u about... hope i could help...:)