Systems, methods, and software can be used to write system software on an electronic device. In some aspects, an instruction to write system software on an electronic device is received from a booting device that is different than the electronic device. In response to the instruction, a boot loader on the electronic device is invoked. A password is received from the booting device. Whether the received password matches a high level operating system (HLOS) password stored on the electronic device is determined. If the received password matches the HLOS password, the system software is written on the electronic device. If the received password does not match the HLOS password, the writing of the system software is halted.