Locked up 250 manual trans will show it is neutral but I can not even push it. The back tires even in N will not move. I checked the brake lines and it appears they are working fine. If the trans need oil I can not figure out where to put it.

why not scan the PCM first (OBD2?)
2wd or 4wd ?
no miles told on car, 300k miles>? or?
NO year or VIN or Engine told. 2002 to 2012 .
"I pulled it means ",you out side car pulling it to move it brakes all off? I can not understand this statement.
so sorry .
but have done it vast times (pushing), and checked brakes. and inspected brakes for rotor warp ,cracks or calipers seized. *and hand brake fails, car must be in neutral to push it. (park locks rear wheels)
and seems key to me.
ok brakes are failing or the engine is weak
so if brakes are not failing then the engine is weak.
it's not slipping transmission as RPM are low.
i can name 50 causes and 10 to 20 tests
top cause is low fuel pressure.

engines used (not told)

"the 150 horsepower (110 kW) 2.4 L straight-4, which was discontinued in 2006, and the 210 horsepower (160 kW) 3.7 L V6, as well as a short-lived 2.8 L VM Motori turbo diesel (2005-2006 only).[6]
2008 I4 dropped and , diesel to dropped"
only 3.7L V6 (a fine engine I have,)
my V6 is chain drive cam and very strong.
when power is lost we put in a new ACC belt,new filters and new spark plugs. called a tune up, ever do one?

the belt new saves engine overheat damage $$$$$$$
my v6 (2010 grand Cherokee)
uses 4 things to make power. (besides spark not bad)

1. a working FPR (fuel pressure reg.) a tool
2. good fuel pump both are tests using gauge tool PSI. (service manual covers all this)
3. or even bad fuel, in the tank.
4. and working MAP sensor and for sure not clogged up.(vac port end)

and more, bad engines happen... compression tests.
I use the scan tool and PID scan every sensors in the on the engine, and no DTC errors.

and make sure ECT reads 180F+ when engine is fully warm/hot. if way LOW the thermostat is bad.
most 11 year old thermostats (car 2012) are bad.
or older car. I'd not run one over that. risky to engine,.
tell more get more.
do a tune up fully
scan it.
clean the MAP fully
full brake inspection any time car can not be pushed by hand in Neutral. key off. (not park ) hand brake off.
yes hand brakes fail too ,rear. this brake is small drum brake and can seize, main brakes are all calipers x4
all can cause seize up.(or be intermittent !!!!)

if car has brake problems do not drive the car fix it first.
even ABS can fail. (I purge mine every year DOT fluid)
ok there are some ideas, to try.

my guess is brakes bad or was in PARK
if not scan the engine.

Automatic transmission, time for a rebuild. Manual transmission, clutch package, master and slave also.

Sounds like your linkage adjustment slipped. Chock your tires...jack up if you can't fit underneath it...have a helper move shifter back and forth so you can locate where it attaches to transmission. When you find it, have your helper move it from low to park slowly. When you see what way the piece on trans is moving, loosen the adjustment screw, manually place trans in park, then tighten adjusting screw.

try bringing it in the front door but I don't think that will fix the problem. if the wheels are locked up there is a safety switch that will not let it start if the trans is in gear

Think you have simply frozen your piston from lack of proper fuel and 2 stroke oul mixture. Bike will move in neutral and with the clutch in, just won't kick or bumpstart ! Time for a top end rebuild my friend...good luck !

The odds are that it will have to come out
& be rebuilt

Even when you do that, you usually don't
actually find much,but the issues go away.

I once owned a trans shop

What i would start with is jack up the rear two tires and try to freely move them with your hands.

If they are locked in place then you have a problem with your rear brakes.

If the back ones both turn freely. Then move on to the front and jack up the front of the car.

You can check to see if the transmission by either turning on the vehicle and putting it in drive with both front tires off the ground and see if both spin freely. If one if them locks up then you have a problem with your front brakes.

Take it one step at a time and check everything out brake wise again, even though you latched and released the parking brake the spring mechanism could be broken and locking it in place.

Your rear emergency brakes could be hung up. Especially if a parking valet or someone else parked it recently.

You need to jack up both rear wheels and then put your car into neutral with the motor OFF. If the rear wheels can not be manually turned it is either the emergency brakes, the differential or the transmission.

The emergency brakes require removing the back tires and rotors. If it is still locked, then it is either the differential or the trans. The driveshaft connects the trans to the differential so remove the driveshaft. If the differential turns without the driveshaft, then the trans is locked up. If the differential does not turn the problem is inside the differential.

Yes under the hood on the trans is the linkage. Pull that off the trans (should be a clip) and move the lever it was on. If that is stuck it is the trans.

Most likely you have a trans range/neutral safety switch on the transaxle bad or misadjusted.Or you have a Line pressure actuator failed inside valvebody.