I was experimenting with the GPIO ports when I think I might have shorted pin 18, though I'm not sure how. Now, GPIO pin 17 and 18 are stuck at logic high.
The two pins remain at logic high despite multiple reboots. I've tried changing the logic level on those two pins using Python RPi library, and WiringPi with no effect. If I power off the Raspberry Pi but keep the power supply on, the logic levels on both pins also remain high. The same thing happens when I boot up the Raspberry Pi without the SD card inside.
I've tested other pins and they seem to be alright. Raspbian boots up fine with working USB ports, HDMI display, sound and Ethernet.
Does this mean I've permanently damaged the two GPIO pins?