I am in similar though not identical situation. We live in Chicago.

Last autumn we bought a few bamboo plants in pots (brand Monrovia).

We had no room indoors, and the store recommended that we winter them
in an unheated garage, giving very little water but no food. We that
and took them out in the Spring. However, they haven't come back to
life at all, although I can't pronounce them dead with any confidence.

How long should I wait, and how should I treat them, re food/water etc.
They get a few hours of sun everyday.