Ace3ds PLus wood firmware. If you have the ace3ds plus flashcart, just use this wood firmware. Download it, extract it, put all the contents on the root of your sd card.
Source: http://www.thegamerdepot.com/ace3ds-pluscheapest-flashcart-working-great-on-3ds3dsdsids-p-153.html
Source: http://www.thegamerdepot.com/ace3ds-pluscheapest-flashcart-working-great-on-3ds3dsdsids-p-153.html