  Black hole X-ray binaries (BHXRBs) play a crucial role in understanding the
accretion of matter onto a black hole. Here, we focus on exploring the
transient BHXRB \source~discovered by Swift/BAT and MAXI/GSC during its January
2019 outburst. We present measurements on its accretion properties, long
time-scale variability, and spin. To probe these properties we make use of
several NICER observations and an unexplored data set from NuSTAR, as well as
long term light curves from MAXI/GSC. In our timing analysis we provide
estimates of the cross-correlation functions between light curves in various
energy bands. In our spectral analysis we employ numerous phenomenological
models to constrain the parameters of the system, including flavours of the
relativistic reflection model Relxill to model the Fe K$\alpha$ line and the
$>15$ keV reflection hump. Our analysis reveals that: (i) Over the course of
the outburst the total energy released was $\sim 5.2 \times 10^{44}$~ergs,
corresponding to roughly 90\% the mass of Mars being devoured. (ii) We find a
continuum lag of $8.4 \pm 1.9$ days between light curves in the $2-4$ keV and
$10-20$ keV bands which could be related to the viscous inflow time-scale of
matter in the standard disc. (iii) Spectral analysis reveals a spin parameter
of $\sim 0.6 - 0.7$ with an inclination angle of $\sim 45^{\circ}-70^{\circ}$,
and an accretion rate during the NuSTAR observation of $\sim 17\% ~L_{\rm
Edd}$.
