  Massive black holes (BHs) at the centres of massive galaxies are ubiquitous.
The population of BHs within dwarf galaxies, on the other hand, is evasive.
Dwarf galaxies are thought to harbour BHs with proportionally small masses,
including intermediate mass BHs, with masses $10^{2} < M_{BH} < 10^{6}
M_{\odot}$. Identification of these systems has historically relied upon the
detection of light emitted from accreting gaseous discs close to the BHs.
Without this light, they are difficult to detect. Tidal disruption events
(TDEs), the luminous flares produced when a star strays close to a BH and is
shredded, are a direct way to probe massive BHs. The rise times of these flares
theoretically correlate with the BH mass. Here we present AT2020neh, a fast
rising TDE candidate, hosted by a dwarf galaxy. AT2020neh can be described by
the tidal disruption of a main sequence star by a 10$^{4.7} - 10^{5.9}
M_{\odot}$ BH. We find the observable rate of fast rising nuclear transients
like AT2020neh to be rare, at $\lesssim 2 \times 10^{-8}$ events Mpc$^{-3}$
yr$^{-1}$. Finding non-accreting BHs in dwarf galaxies is important to
determine how prevalent BHs are within these galaxies, and constrain models of
BH formation. AT2020neh-like events may provide a galaxy-independent method of
measuring IMBH masses.
