Striker Julio Tavares scored in first-half stoppage time to Cape Verde in the Olembe Stadium of Cameroon.
Coach Bubista and nine Cape Verde players were absent because of COVID-19 and the Blue Sharks were only able to name six substitutes for their match against Ethiopia.
The east Africans went down to 10 men early on after Yared Bayeh failed to control a wayward back header and brought down Julio Tavares just outside the box in the eighth minute.
Initially shown yellow by Angolan referee Helder Martins de Carvalho, the centre-back had his card upgraded to red after a lengthy VAR check.
Substitute Mignot Debebe almost scored a freak own goal, but his miscued clearance was clawed away by Ethiopia keeper Teklemariam Shanko on the line, and Shanko then saved well from midfielder Dylan Tavares.
The islanders hit the front when a deep cross from the left flank was volleyed back across goal by the ever-bright Garry Rodrigues and striker Tavares was on hand to convert from close range.
Ethiopia made little impact going forward in front of a sparse crowd, with the majority having departed after Cameroon’s earlier victory.