After waiting for a while, the status info in QFlash changes to “[COM0]Download fail[Open port fail]!” which is very strange because I don’t even have a COM0 on my computer. All the available COM ports are shown in the device manager screenshot.
I tried on a different computer, and it worked flawlessly. I borrowed an old laptop from the office for flashing, and gave up on trying to solve the problem on my main dev machine.
@prash hi, first connect the module to PC through usb to uart cable, then open Qcom through USB AT PORT send command AT+QDOWNLOAD and send enter. it replies with okay. This makes the module to be ready for download mode. After this SPRD U2S port would be enabled which is for firmware download.