Two long-standing communities are known for hosting unmodified stock ROMs:
(If you want, I can draft a short step‑by‑step flashing guide for the ZTE Blade A55 tailored to stock or custom firmware—specify which.) firmware zte blade a55 link
to find the correct after-sales service manuals or firmware labels. Flashing Tools for Unisoc SC9863A1 firmware zte blade a55 link
Note: The ZTE Blade A55 likely uses a or MediaTek Helio chipset. The flashing method depends on this chipset. firmware zte blade a55 link