hmmm... a custom made laptop.
That beep is a fault code, it usually can mean faulty memory or graphics. but without the board manufacture and model number it's not too likely we can find out what that fault code means.
Try one stick of memory at a time in each slot and rum Memtest to determine if it could be a bad memory module. You can use the free edition
MemTest86 - Download now!
If the graphics processor is soldered on the board, then there's no way you can fix that yourself. You could try connecting an external monitor and see if it'll post. Check your keyboard for any stuck keys too, if you had it packed, one of the keys might be jammed down