Multiple Problems With My Nv7802u

I purchased a NV7802U laptop a little over a year ago.  While using, the power cord to laptop started fizzling and smoking.  I unplugged and bought a new power cord (21.99).  After 1 day of using power cord, the computer completely went dead.  I took to consultant and was told the mother board was bad ($40.51).  I called Gateway and Best Buy and was told that my warranty had expired 12 days prior and there was nothing they could do.  I purchased a new mother board and had put in ($299.00).  Computer started up but the screen was barely visable.  I took back to consultant and was told that a new screen was needed.  I had them replace the screen (143.00).  Brought laptop home and now the battery will not charge.  I can use but always has to be with the power cord.  I have been looking online at the Gateway and Best Buy websites for a replacement battery and have not been able to find anything on this computer model number.  I have spent over $500.00 to get this computer fixed and it is still not working.  Was this computer possibly recalled for similar problems and that is reason I no longer see on website?  I am frustrated as I am still paying on the original purchase through Best Buy.  I have all the paperwork for repairs as well as paperwork that came with computer.  I have struggled financially to get this computer repaired and am not sure where to turn from here. Could you please let me know how to find a new battery for this computer?  I see on website that there is a battery for a NV78 but I am not sure if it is compatable.  I would hate to purchase just to fry the motherboard again.    Have other people experienced this problem?  My daughters rely on this computer for school purposes. Is there any type of return policy or free replacement policy?  I do not know where else to turn.  I appreciate all your help and hope for a speedy reply.  Sincerely, Kim Hobbs9108 Wood RoadAlbany, Ohio  45710(740) 698-2337 home740-541-0284 -cell