Yes you can do it by yourself by reading the ifixit' s menu. But it's really not recommend because your phone will lose the ability of waterproof and there's a extremely high chance that you will damage your phone. Go ahead if you don't mind taking a risk.
******I'm not responsible if you damage your phone. Do it on your own risk******
Follow these steps:
1. Take a suction cup, heat gun, heat glue, tweezers, soldering iron
2. Turn on the heat gun and set the temperature at around 80-85C, heat the whole phone. Remember not to heat the battery to much!
3. Take a suction cup, suck it onto the phone. Try to pull it out, if it still sticks, turn the heat gun to around 90C. Heat the edges for a short while. (Don't melt the suction cup!!)
4. take the tweezer , and peel away those adhesive tape away asap or not you will have a hard time with them.
5.When you remove them all, you will see the motherboard and the battery, unplug the battery first.
6.Then remove the motherboard. And the thermal paste
7. you should see the bent sim tray, heat the soldering iron up, after heating, try to remove the sim card first because you have a high chance of damaging the sim card. Then, put the soldering iron onto the bent sim tray.
8.Take the tweezers, try to bend the bent area. Then pull the sim tray out.
9.Put the sim tray aside. Unbend it with your own way.
10. Now start resembling the phone. YOU MUST PUT THE BATTERY CABLE BACK!! Take some good thermal paste like Nt-h1. Don't put too much! After putting those sticky adhesive tape back. Use hot glue and put it on the edge of the phone. Put the phone's back cover back to the phone.
11. You should be okay now. Now boot your phone!
12. That's all! good luck ^_^
Warning: your phone may still be waterproof but not as good as before
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This could probably happen to a iPhone too.. I'm guessing this part is where the frame is bent as that is somewhat part of the sim tray holder too.
by Ben