Arduino Micro suddenly unable to complete upload

I've been using an arduino pro micro (http://www.dx.com/p/diy-atmega328p-16mhz-electric-block-module-blue-172858) for a project., to read sensors and output serial data. I attached a 3.3V boost regulator (http://nicegear.co.nz/electronics-gear/ncp140033v-stepup-breakout/) to the arduino to power it from 2 * AA batteries, and now it behaves weird, even after removing the boost regulator and trying the usb 3.3v power supply used to initially program it. Now I am unable to complete download to the arduino. If I check the serial monitor, the arduino is sending back serial information from the sensors, but the values remain constant now (wondering if sensors have been fried?) (sensors are a single axis gyro, 3-axis accelerometer, both take 3.3V). If I try to upload from my computer, the arduino lights flash like they normally do when it receives new code, but then nothing else happens. The arduino programmer software just continues to report "Uploading..." (have tried leaving it for minutes), and never ends. I have tried uploading simple analogread example and then just restarting the software after about 30 seconds, and then the serial monitor still reports that the arduino is sending back sensor information from the original sketch. I have also tried uploading to an arduino uno, and that works fine as expected. I have checked serial port and board type for the arduino micro in the software.

If the lights flash when I press upload, it must be receiving something? And I am also able to receive from the arduino, so I don't know what the problem is, or how I could have fried the arduino. Does anyone know what the problem might be?

methyl: I've been using an arduino pro micro (http://www.dx.com/p/diy-atmega328p-16mhz-electric-block-module-blue-172858) for a project., to read sensors and output serial data. I attached a 3.3V boost regulator (http://nicegear.co.nz/electronics-gear/ncp140033v-stepup-breakout/) to the arduino to power it from 2 * AA batteries, and now it behaves weird, even after removing the boost regulator and trying the usb 3.3v power supply used to initially program it. Now I am unable to complete download to the arduino.

Which pin did you connect the 3.3V boost regulator to? "Raw" or "Vcc"?

The 16MHz version you have is actually a 5V board. It should run fine if you apply 3.3V to Vcc by itself, but it would be inadvisable for you plug something else to "Raw" (i.e., Vin), which will both try to raise the Vcc voltage to 5V. The linear regulator on the pro mini would be fighting with your boost regulator. I don't know if your boost regulator would simply shutoff under these conditions, or whether something worse would happen. But in any case, probably not a good idea.

Similarly, if you have your boost regulator connected you don't want to power Vcc via your USB/TTL adapter cable unless it is also supplying 3.3V to Vcc.

If you have access to a ISP programmer, I'd advise trying to reload the bootloader, to try to get things back to a known state. Disconnect the boost regulator while doing this, and see if you upload after that, just powered from USB.

The boost regulator is connected to Vcc. I have tried removing the boost regulator and powering Vcc from the 3.3V pin on the USB/TTL adaptor, but still I get the same result. I have also tried re-burning the boot loader, but the arduino software tells me there is no USB connection, even though the serial monitor still reports text incoming from the arduino.

methyl: The boost regulator is connected to Vcc. I have tried removing the boost regulator and powering Vcc from the 3.3V pin on the USB/TTL adaptor, but still I get the same result. I have also tried re-burning the boot loader, but the arduino software tells me there is no USB connection, even though the serial monitor still reports text incoming from the arduino.

Have you tried powering on "Raw" (i.e., Vin) with 7-12VDC?

To burn a bootloader, you can't do it over the USB/TTL serial cable like a sketch, you need a ISP programmer, like a USBasp or similar.

It's also a bit more tedious on a Pro-mini than a normal Arduino board because there is not ICSP header. You just have to connect to the spi and reset pins by some ad hoc arrangement (probably using a breadboard would be most straightforward, if you have one.)

Try the "Raw" test first. Disconnect the 3.3V supply from your USB/TTL cable, but leave the other pins connected.Connect7-12VDC to "Raw" (Vin). See if you can get a monitor connection, and then try to upload a sketch. You will be running Vcc at 5V in this arrangement, so of course your boost regulator must also be disconnected for the test.