OK, right out of the gate, Windows 7 does not have USB 3.0 drivers. This is where people trying to install it in later boards, particularly Intel Z-170 and above, failed, Especially in systems with no DVD drive. With a USB (2.0) stick install, Win 7 just stalls at the point it encounters the need for USB 3.0. It can be installed with a PS-2 mouse & Keyboard from DVD. However, most recent boards only have a single port.
I know for a fact that some Gigabyte Z-170 boards w/EUFI BIOS have a setting known as "USB 3.0 hand off". In other words, the board supplies the 3.0 driver until the OS is fully installed, finds the 3.0 driver, and then can be set to "hand off" control of USB 3.0 to the OS.
I know absolutely nothing about your board, it's vintage, or anything else about it. Consider this background information, nothing more.
However IF, you board has the 3.0 driver and has the USB 3.0 hand off function, it could be a simple BIOS / EUFI setting, not a flash..
From DVD, a Windows >repair< reinstall, has worked wonders for me regarding startup issues. However this was for a much earlier machine, I have no clue whether or not it has any relevance in your situation.