  Emission spectra of hot accretion disks characteristic of advection dominated
accretion flow (ADAF) models are investigated for comparison with the brightest
ultra-luminous source, X-1, in the galaxy M82. If the spectral state of the
source is similar to the low luminosity hard state of stellar mass black holes
in our Galaxy, a fit to the {\it Chandra} X-ray spectrum and constraints from
the radio and infrared upper limits, require a black hole mass in the range of
$9 \times 10^4 - 5 \times 10^5 \msun$. Lower black hole masses ($\la 10^4
\msun$) are possible if M82 X-1 corresponds to the high luminosity hard state
of Galactic black hole X-ray binary sources. Both of these spectrally
degenerate hot accretion disk solutions lead to an intermediate mass black hole
interpretation for M82 X-1. Since these solutions have different spectral
variability with X-ray luminosity and predict different infrared emission, they
can be distinguished by future off axis {\it Chandra} observations or
simultaneous sensitive infrared detections.
