This game neglects to disable mapper IRQs (used for scroll splits) on reset, causing it to not boot in some circumstances (see second image for an example of this). This hack fixes the reset handler to keep mapper IRQs disabled until the game has initialised, making resets consistent.
The patch works with both USA and JP versions of the game.
Database match: Mega Man 5 (USA)
Database: No-Intro: Nintendo Entertainment System (v. 20210216-231042)
File SHA-1: CFE3B9A0D70F36E5D77C2DF353432C6042929B1E
File CRC32: BD918F62
ROM SHA-1: 36842491BB513C80BEB9F2FB2AA30EDAA1121CA4
ROM CRC32: 3EDCF7E8
Database match: Rockman 5 - Blues no Wana! (Japan)
Database: No-Intro: Nintendo Entertainment System (v. 20210216-231042)
File SHA-1: 1616C4B3B25B6DBB14EEE506F0ECA32E7E477F3B
File CRC32: 7E9259BF
ROM SHA-1: 36A89DA160D9760F78B891E332F7DCABB6E90E70
ROM CRC32: FDDF2135