Obvious things first: Carefully double-check everything that you did. Watch out for solder bridges (either fat ones or hard-to-see whiskers). Make sure that you disconnected what should be disconnected, and connected only that which should be. It's easy to miscount pins, for example, and be off by one or two. Count up from the first pin, and also count backwards from the last pin, just to make sure you get the same answer both ways. This simple trick has helped me out many times (it's hard to doublecheck your own work, because you know what you intended, so that's what you tend to see; counting backwards and similar tricks forces you to use different neural pathways).

Next, a 5-minute interval is very long for anything purely electronic, and is suggestive of a thermal problem (possibly induced by miswiring). The fact that it ultimately shuts down is itself serious. The additional fact that you get simultaneous brightening and enlargement is extremely worrisome, because these two symptoms together imply a gross increase in beam current, and a diminution in high voltage (probably caused by the excessive beam current loading down the HV supply). I wouldn't be surprised if you noticed degraded focus at the same time.

If you can't find a wiring error, then you have a complicated troubleshooting session ahead of you, I'm afraid. Someone here can walk you through the next steps after you report back.