  We describe the phases of a solvable $t$-$J$ model of electrons with
infinite-range, and random, hopping and exchange interactions, similar to those
in the Sachdev-Ye-Kitaev models. The electron fractionalizes, as in an
`orthogonal metal', into a fermion $f$ which carries both the electron spin and
charge, and a boson $\phi$. Both $f$ and $\phi$ carry emergent $\mathbb{Z}_2$
gauge charges. The model has a phase in which the $\phi$ bosons are gapped, and
the $f$ fermions are gapless and critical, and so the electron spectral
function is gapped. This phase can be considered as a toy model for the
underdoped cuprates. The model also has an extended, critical, `quasi-Higgs'
phase where both $\phi$ and $f$ are gapless, and the electron operator $\sim f
\phi$ has a Fermi liquid-like $1/\tau$ propagator in imaginary time, $\tau$. So
while the electron spectral function has a Fermi liquid form, other properties
are controlled by $\mathbb{Z}_2$ fractionalization and the anomalous exponents
of the $f$ and $\phi$ excitations. This `quasi-Higgs' phase is proposed as a
toy model of the overdoped cuprates. We also describe the critical state
separating these two phases.
