E7240 died after trying to fix dock!

I appear to have killed my Dell E7240 laptop while attempting to fix my docking station.

I was using my laptop off the docking station, and using the battery, last night. When I finished I put the laptop to sleep and put it in the dock.

This morning when I tried to turn my laptop on nothing happened. I noticed that all the lights were off on the dock and the light was off on the Dell charger cable even though it was plugged in.

I took the laptop off the dock and it worked fine. I tried the charger in a different socket and it was fine and when I put it back in the original socket then it also seemed fine. The light indicator lit up and I was able to plug it into the laptop without issue.

I put the charger back into the dock but it gave no signs of life. I tried putting the laptop onto the dock with the charger plugged directly into the laptop rather than the dock. When I did this the lights on the dock lit up for a split second and then everything died, the dock, the laptop and the charger.

The charger is fine again now once I unplugged it and plugged it back in but the laptop is dead.

When the charger is plugged in then the battery and power indicators on the outside of the laptop light up. When the laptop is on the battery (which had 63% charge before it died) and I press the power button then the external battery and power indicators light up for a few seconds and then go out. Nothing else happens.

None of the storage, battery or power indicators above the keyboard light up at any stage.

I've tried taking the battery out, unplugging the charger and holding the power button in for 30 seconds but it hasn't made a difference.

Any suggestions would be greatly appreciated.