Inspiron 3847 - Flashing Orange Light at Back of Desktop - Should I Worry?

Hello

Firstly, I should say I have no idea about any of the workings inside my computer so all help is gratefully received.

Today I noticed a flashing orange light at the back of my desktop tower. Now it might have been there since day one but I imagine I would have noticed it before as the tower is on my desk...

The light is just above the area where the modem cable plugs in. Inside the computer (and here I show my lack of tech knowledge) there seems to be a small box like structure on the motherboard in the area the modem cable plugs into and I can see the light flashing from that. There is a constant orange glow just above it (also emanating from around that box area). The area does not feel hot. Fans are working.

I have turned it on and off and have unplugged the modem cable and plugged it back in but the light continues to flash.

The tower did fall over onto its side about three weeks ago (on a flat surface so not far and it was switched off at the time) but it has worked fine since. 

Mountain out of a molehill? Or serious issue? 

Thanks