Sometimes it is possible in Nicaragua to open a bank account without being a resident. It will depend on the bank and if the potential client can prove his/her source of income, so a letter from his/her bank at home will work. Also very helpful would be a letter of reference from a Nicaraguan.
It will be also very useful if the applicant can prove he/she is in the process of obtaining residency in Nicaragua.
Some banks have bilingual executives or branch managers, so it will more comfortable to identify this in advance if it is a concern for you.
To open a bank account for a business purpose it will be imperative to have a corporation duly incorporated registered.