I have recovered a few "blown" motors in my time so try the below IN ORDER.
This stuff is not hard for someone with basic tools and WILL save you paying for
unneeded repairs. At least you will know the extent of damage.
1.Release pressure from fuel filter/line/system. Remove injectors, set aside wrapped in clean rags wet with fuel/oil
2.Socket on main crank pulley nut,turn in direction of rotation ONLY, arrow should be cast into block.
3.Turns yes/no. If yes, drain oil into MEASURED container and check volume and colour. If it looks new, all good. If it looks like brown metal flake paint, not so good, chunks even worse. Anything bigger than grinder swarf is BAD. :'(
4. If not turning, Remove sump and inspect carnage. Feel around for any obvious movement. Parallel to crank rotation is ok if very slight ie you can JUST feel it, any movement across the crank rotation is
4a. Remove bigend caps taking note of which one goes where and in what direction as this does matter, inspect bearings on rod and crankpin(the round bit the bearing cap was around) anything you can feel with a fingernail is no good.
4b. (get it, 4b?? haha) If 4a is ok put all the rod caps back on, but not tight for now. ONE by ONE remove main bearing caps ie take one off,inspect, return back to place. If you take them all out your rods,pistons and crank may fall out onto your chest/crossmember.
They wont, unless of course you have the engine seperated from the gearbox.
4c. By now you will have discovered significant damage. Assess and get repairs/repalcement.
5. If turns and oil is good, refill with new oil TO SPEC quantity and new filter. Check starter for stuck pinion and exploded windings which will produce both the inability to start the motor, a shirtload of noise as the stator flogs about plus a click click when trying.
6. Re-assemble and try for re-start.
All up, the above verification should take no more than a day of fun. Hopefully might save some coin too. If not, then at least you know.