So far you seem to have made one posting Galileo Gen 2 UART, a few hours before this one which didn't seem to ask any question aside from asking if a 3.3V from the Arduino would power the Galileo, which it can't, otherwise you just stated what you were doing. People here are doing this on their own time, so you won't get immediate answers, and if people can't figure out what you are asking, they will just move on. So for a start, you should ask specific questions, give more information and close this postings. You should also go to this page Intel Galileo Support and see if you can find your answers. You can also contact Intel support.
I don't see how leaving it underpowered on a mat would destroy it. Was it powered with the supplied power supply? Did you use stand-offs so you could have some air flow so it wouldn't overheat? Do any lights come on?
If the Galileo is left in the anti-static bag, with no power, it is not likely to be damaged, unless you do something else. Now if you try to run the Galileo while in the bag, you will probably cause it to over-heat. Putting an SD card in won't hurt the board, unless you try to do it when the board is powered up, and even then it would be rare. More likely caused by you providing a path to ground than from the inserting. The two biggest problems are trying to run it on insufficient power - such as connecting the usb cable to the client port before powering the system, or unplugging the power before disconnecting the client usb cable, or running on batteries with insufficient current - and poor grounding. This isn't an Arduino with a simple, rugged MCU it is a full CPU and static electricity can damage it. If you had sufficient power, good grounding and adequate ventilation, than you need to look at what you had connected to it. Just like with the Arduino, if you try to draw too much current through the pins, you will damage it.
As for using an Arduino instead of a Galileo, that would depend on your purpose. If you want to do something simple or that requires precise timing, than yes, use an Arduino. It would be a waste of resources to use a system as powerful as the Galileo for a simple sensor module. If you want to do something complex or that needs to be multi-treaded, than you will quickly find the Arduino doesn't have the horsepower.
This probably hasn't answered your question, but you need to be more specific as to what you did and want to know.
Sorry if I seemed angry, sometimes I type before thinking. I did as you said only ask 1 question about the serial compared to the FTDI but figured it out myself then I asked if the Arduino 3.3v line is good or if I should use a LM317 since I had no answer I decided to use an LM317 but was gonna do it in the morning. I left my GAlileo with NO power on my ESD mat for the night. I decided in the morning before trying to reflash, I would see if it was my windows 8 computer not reading it right (I have read posts of 8.1 giving issues) I grabbed my laptop, attached my wrist strap and plugged in my Galileo but no lights powered up. I agree with you that none of those should brick/destroy the Galileo, as for air flow, I have an old CPU fan always blowing on it a small oscilattin fan on me and my power supply blows pretty good, I never ran it in the static bag (I worked for an electronics company and we had an employee who killed a couple board leaving them powered and putting them in a bag.) I am always grounded and and always working on my ESD mat. The reason I asked if there was a technical forum is as I said this seems to code based and I am looking for hardware, I also though this was part of the intel support so that is my bad. I will remove this post. I would like to add I do love the idea of a full out computer with arduino pinout but my experience has been negative.
You can mark it as answered.
If you power the unit with the supplied power supply through the on-board regulator and no lights come on and the CPU remains cool, you probably have damaged the hardware. You should only use the supplied power supply or you have to be very careful to insure you don't exceed the power limitations.
You can contact Intel warranty and they will walk you though the steps to test it or follow the lead I gave you earlier