lift the hood take pictures & share, please
-
check engine oil (pull dipstick clean, reinsert and check oil condition)
remove the radiator cap & check coolant / water
remove air cleaner cover & check the filter
check fuel tank add 10 liters of fuel to it - close CNG valve.
jump start cable & a healthy battery (or another vehicle with idling engine to jump start)
if all seems in order jump start the engine, do not throttle let it idle for 10 - 30 seconds.
drain old expired engine oil. flush engine with flushing oil.
drain and renew engine oil & use only new oil filter (use 5W-30 grade only)
remove wheels get all 4 checked, balanced & fixed to correct air pressure.
engine working, get compression test done, dry & wet readings shall not be under 150 psi over all 3.
rest of mechanical stuff can be managed conveniently., if engine compression readings are over & above 160 - 170 psi.