RecruitingClinical trialCombining Spinal Cord Transcutaneous Stimulation and Activity-based Training in Inpatient Rehabilitation to Facilitate Upper Limb Function of Individuals with Acute to Subacute Cervical Spinal Cord InjuryThe purpose of this clinical trial is to understand the safety and practicality of using spinal cord transcutaneous (through the skin) stimulation in an inpatient setting as well as how the combination of activity-based training (ABT) and spinal cord transcutaneous stimulation (scTS) can improve participants' ability to use their hands, arms, and trunk in an inpatient rehabilitation program. The main questions it aims to answer are: * Is the combination of spinal cord transcutaneous stimulation and ABT is safe and practical when applied to individuals with acute to subacute cervical SCI during inpatient rehabilitation? * How the combined intervention can improve hand and arm function when applied to those individuals? The investigators will assess the safety, feasibility, and preliminary efficacy of the combined intervention and compare to a sham control (sham stimulation combined with ABT) and a ABT only group to see if the combined intervention can lead to greater function recovery. Participants will: * Receive one type of the three intervention (scTS+ABT, sham scTS+ABT, or ABT only) for 10 sessions with 30 mins/session over 2 weeks. * Receive assessment before, during, and immediately after the intervention, and at 1-month, 2-month, and 3-month follow-up visits.