Axum was one of the 4 most powerful and advanced countries in the world. But then the trade routes were destroyed, they lost control of the coasts and the coptics retreated to the highlands.
Ethiopia from about 900 onwards was weak and backwards because it was cut off from the world's markets and from the worlds ideas.
Goods from axum could be found all across the continent, goods from the ethiopian highlands were not.
Ethiopia from napoleonic times onwards was a backwards feudal country with no local allies, no real centralised state, a monarchy that was not strong enough to reign in the nobility, poor marginal land, deep religious divides and an army that simply wasn't capable of fighting on equal terms with european armies.
Could a post napoleonic ethiopia do better than otl? Yes. The ethiopia in male rising for instance does rather well for itself by becoming russia's puppet in a scramble for africa done via proxies rather than direct control.
Could it ever become a world power with a pod post 1800? No.