I have a Z530. It's the second one: the first died after trying some tricks with a hacked version of russian Opera Mini 1.2. It was replaced under warranty. I think it could've been revived by re-flashing the firmware but they replaced it. And took over 10 days to do it.
So, I got a new one, it worked fine. On day 3 I open it up and it clicks... and it no longer holds open, WTF?! So, I take it back to service, and they say it can't be repaired because i must have hit it. "Lo has de haber abierto muy fuerte" was the wording used.
Hell with it, since they said my warranty was void already, I came home and pried it open. The spring works like the one on retractile pens, so you would have to break away the joint before you would damage it. The whole thing is held by a metal ring that broke, I used a loop of wire to replace it. I thought it wouldn't last a day but it's been fine for over a year. I also replaced the spring and used a softer one.
I had never had any problems with any SE phone, but I really got ticked off with that. It makes you think again about how much your warranty is worth.
BTW I live in Mexico and this was on the SE service center at Polanco. It's the only authorized service center in Mexico city. They are lame at identifying actual defects from user damage: i had a K300 dropped and the mic died, and they repaired it.
Anywhere else with warranty problems? Anyone knows how to complain to SE?