Hey guys, Ive been looking into another 1987 TV, low miles and in minty fresh condition.. but they crossed the jumper cables and now it will not start. Apperently there is power to the cab, lights, radio work. but nothing when you turn the key besides possibly a relay clicking.

Any insight to what fusable like could be causing this? Ive done some extensive research and havent stumbled upon the right answer yet.
Thanks in advance guys!!