Eroor Propagation

Basta-Pilot-Steady-Switch-LEDOk, it was 1 am as I switched off the TV and only than I remembered I had to fix the flat tire on my kid’s bike. No biggy, this would only take 20 minutes, so I get my gear and start to work. Bummer, I need to take out the wheel, the leak is too small to hear. Ok, maybe 30 minutes, no worries. So I disengage the hub dynamo, noting the plus wire has a white stripe on it. I find the hole, fix it, reassemble the tire, and in my head I am already in my bed, in just 2 more minutes everything is properly reaffixed. I test the light as a matter of double compulsion. After all I am both a coder as well as a caring father. The light refuses to work. Maybe the connector is dirty. I start debugging, working my way up from the hub to the lamp. Twenty minutes later, I have the whole thing off the bike, stripped naked on the table and I take my multimeter to it. I curse these digital IC controlled lights. It used to be so simple. Just one wire connecting a dynamo and a bulb. (Or spit into the carbide lamp.) Whoever asked for a “wunderlamp”? After an other five minutes, I find out the bulb looks ok, but the meter tells me it’s broken. Curses! Why did my kid not tell me her light needed fixing? I would have checked the bulb first thing. Because of the flat tire I started debugging at the wrong end. Because I assumed the light was working before, I assumed the connector was the most probable thing to be at fault. That good all MOAFU called assumption. It is bad enough that I have to endure bad error propagation at work, but from my own blood?