Export axmodel layer example :
Export-AXModel -Model CUS Model -config MicrosoftDynamicsAXUAT -file CUS.axmodel

Import axmodel with replace and create parent example :
Install-AXModel -File CUS.axmodel -Conflict Overwrite -Config MicrosoftDynamicsAXUAT -createparents

reference link :
http://axbloggerblog.blogspot.co.id/p/powershell-commands.html

do full compile, full sync db, full CIL and incremental. Re-deploy website EP if you are customize the EP