I have been having the same problem with the Samsung Blaze; in fact my problem started in at the end of February 2013 (2 months after purchasing the new phone). I have for the past 2.5 months been managing to get by by taking in stride that sometimes it charges, sometimes it doesn't. I've bought a new cord, that seemed to work a few days, then it was back to doing the same thing. I had gotten a battery pack back up charger upon my purchase and since the problem started I had been able for a while to get the phone to charge by hooking up the battery pack to the phone and then that to the charger, but recently that has been failing too.
I've taken the battery out numerous times in case it was loose but that has not resolved the problem. I brought my phone to the store I bought it at yesterday (had paid up front for it- about 350 dollars for it) and the manager claimed he'd never heard of this issue, which I found surprising after having seen multiple other people describe this problem with Samsung. I was told that I would need to send my phone in to have it looked over which could take 7-10 days, that I would not be given another phone to use in the meantime, because I had switched my account from post-paid to pre-paid when I purchased the new phone despite having been a T-mobile customer since at least 2004 and that I would not be credited for the air-time that I could not use either phone, text or data due to not having a phone.
The manager gave me a spare cord in case that was the issue, but equally that did not work, I woke up to my phone being totally dead, despite having managed to give it a 26% charge after hours of being plugged in.
I would still like to believe that there is some way to fix this charging problem without having to send away my phone and being phone-less for potentially two weeks or more and not being credited for the money paid to Tmobile for this months usage.
I hope that you might have advice? Or that TMobile can offer a reasonable solution....
In the last few weeks, my phone has developed the same problem as your phones. It doesn't charge, or it charges very slooooowly... I tried switching chargers and switching batteries, but the problems persist. Clearly, it's the phone that is malfunctioning. I've had this Blaze for 9 months, and I like it very much. Paid cash, and I don't want to trash it. So my next step is to buy an external charger and swap out charged batteries. If anyone has another suggestion or info about this problem, please let us know.
(1) This charging problem is common for Samsung phones. It also affects Galaxy S3, and well as Notes. Something goes haywire with the charging port (a faulty mechanical connection), and the battery won’t charge properly, or it charges intermittently. It's NOT a problem with the motherboard or firmware. Samsung is apparently aware of this widespread manufacturing flaw, but of course they won't admit it. They just cheerfully fix the port if you’re willing to wipe the phone and send it to them for three weeks.
USB data operations via the cord are not affected by this problem (at least not on my phone) for some reason.
(2) I got my phone to charge by inverting it (putting the charge port on top), and then leaning the phone with the screen angled slightly downward. I suppose it causes gravity to make something connect. Of course, I don't want to depend on this kludge arrangement, so...
(3) I bought a couple of extra batteries and an external charge device. Now I just swap out batteries, and it's unlikely I will ever again charge the phone with a cord.