Huh, that's a real puzzler. Sometimes when you're not working alone it's tough- hard to be methodical, especially when the person who owns the perfectly good car you've just disabled is breathing down your neck.

The main FI relay is sometimes troublesome. Also, is it possible that (your car at least) is having trouble with the hall sensor? They do act up when the engine is hot, although yours doesn't sound quite like the typical case, and I'd guess by the time you had the first relay delivered it would have cooled quite a bit.

As far as the still-dead car goes, any chance you pushed back a pin on the connector? Or, being as how the soder joints on the terminals are where the trouble lies with these, could you have cracked a terminal joint reinstalling the relay? I believe the fan relay is identical- maybe you could switch the two and see what happens.

All in all I find the electrical system in the 740 to be altogether more rationally laid out that that of the 200. The 200 started as the 100, with an incredibly simple electrical system, and then things just kept getting added on, with the result that relays and connectors are scattered all over the car with little rhyme or reason. When the 700 came along the clock got reset, with the result being the excellent relay panel and some other benefits such as fewer (and more modern) connectors. I've heard that if you're in a high salt environment there's been some weakness in connectors on the 700, but on the whole I've found mine to be entirely reliable. When I examine the underhood connectors on mine I see some nice stuff, including silicon rubber sealing boots for each individual pin, an unusual feature in automotive electrical gear.

My gripe with the 700 is physical headroom for the driver (me).