Dell Inspiron 5537 4 beeps

My laptop does not start up, showing up a black screen with 4 beeps, and as this means a memory issue I tries a few steps

- Tries removing both the Rams ( 2 x 4GB) Then 2 beeps turn up.  This generally does mean Motherboard is good.

- Tried interchanging the rams,  this time I don't hear any beeps, but still the same issue blank screen.

- Tried with one ram at a time (both slots and both rams) vice versa. Same 4 beeps.

- Tried with a new single 8gb ram(both slots) ,  still in vain (4 beeps)

Please suggest me, what should be done and what is the problem with. Much needed help.

Thanks.