chevy trailblazer 02

so my dad has a chevy trailblazer 02..4.5L i think.not sure..ok well like couple of 2 months the car once every 2 weeks doesnt wanna turn on...we tryed checking for blown fuses lets say we almost check everything we kan find...the car runs great and everything but the only problem is sometimes it doesnt wanna turn on at all sometimes...we try and try then after trying so many times the car finally turns on but the battery light stays on and if we drive it like that the car smells like burned rubber or gas sometimes..does anybody know what would the problem be?...any help would be great!....

Not a very clear description, wont start means it cranks but won't fire or will not crank?

Not a very clear description, wont start means it cranks but won't fire or will not crank?

like it cranks but wont fire....until we try like lets say more than 10-20 times

Check for fuel pressure and spark when it will not start, basic diagnostics.

Check for fuel pressure and spark when it will not start, basic diagnostics.
were would the fuel pressure be located at?..also the spark means spark plugs correct or no?

Yes this is a coil on plug engine so it is difficult to get to the coils, then you need a specific spark tester the fuel pressure can be checked at the rail or the fuel filter under the truck.