There's very little you can do, apart from opening it up and trying to get serial console access/ playing on its shell. Maybe you can find/ request the GPL firmware for it from Huawei (good luck), maybe tinker from there on.
Nothing of this will really help you with anything, nor are there any bullet point lists to go by, but documenting (e.g. https://wikidevi.wi-cat.ru/) the hardware (SOC-, switch and wireless chips, flash/ RAM size, bootlog over serial) would be 'interesting'. If that's non-Huawei (non-Broadcom, non-Realtek), there would be chances (steep learning curve) - if it's Huawei/ HiSilicon (likely), it's game over for the aforementioned reasons.