Alienware R4 Water Cooling Woes

So for about 3-4 months I've noticed my cpu thermal die reach 90+ degrees while maintaining under it's TJMax of around 100 to no issue. But about five days ago, it reached 100 degrees on core number 4 which in turn gave off warnings like FPS in games would be at 15 FPS due to the CPU not being able to keep up and instant shut offs which I are thankful for so the cpu wouldn't burn out. 

So I investigated the cooler (Closed Loop doesn't mean you can't open it) and found the following, thermal paste was non existent. Blockage in the loops and in the radiator  which had to be cleaned out. Emptied all the factory coolant and put in distilled water (Freshly Made) and cleaned out with Iso Alcohol. Put thermal paste on again and finished. I Put it back on, screwed everything in. For about 30 seconds temp's where at 60 degrees. Then when I opened steam and launched CS GO for an almost load test. The temp rocketed to 90/90/100/100 and windows  became sluggish and shut itself off.

I've read people opened their cooler with no problem, and with other material from people I believe it is possible to do so and put it back, so

What did I do wrong?