Basically, the mexica manage to kill off most of the illegal spaniard expedition led by Hernan Cortez.
No word reaches Cuba about their fate, much less to Spain; thus the Spanish Crown dares no more than a couple of trade posts in the Veracruz coast.
This butterflies away the spanish expedition against the Inca, and without the very specific circumstances in which the spanish defeated them OTL (sucession crisis), they are the biggest empire in the world, very centralized and much more efficent than their north american counterparts. However, they trade with the spanish, and later the rest of Europe.
Eventually both civilizations progress thanks to commercial and cultural contact with the Old World. But the Spanish Empire never rises, and this means a ton of money never enters the european economy.
Will this delay or prevent the industrial revolution?