I could really do with some help, I’ve messed right up here.
On a v limited DIY budget, I would never usually try with electrics but I just needed to switch a pendant light over and it seemed an acceptable “diy” job 
I’ve switched off all the electricity and checked it’s off with a multi meter tool. It’s 100% off. But I think I must have reached the light on the end of the loop, I have 2 black wires, 2 red wires and 1 thick green/yellow striped wire. My new light has 1 green/yellow, 1 brown, 1 blue.
I very stupidly took the old ceiling rose down without taking a photo of how the wires go together, I then put the two reds with the brown, the green and yellow together and the black & blues together.
Switched it all back on and the fuse just tripped. So it’s clearly wrong.
Any ideas?