The shares of our common stock to which this prospectus relates may be issued by us to Roth Principal Investments pursuant to aCommon Stock Purchase Agreement, dated as of May 15, 2026, we entered into with Roth Principal Investments (the “Purchase Agreement”).Such shares of our common stock consist of up to 38,461,538 shares (the “Purchase Shares”) that we may, in our sole discretion, elect to sell toRoth Principal Investments, from time to time after the date of this prospectus, pursuant to the Purchase Agreement. As of the date of thisprospectus, we have not issued any shares of our common stock to Roth Principal Investments under the Purchase Agreement. We are not selling any securities under this prospectus and will not receive any of the proceeds from the sale of our common stock bythe Selling Stockholder. However, we may receive up to $40,000,000 aggregate gross proceeds under the Purchase Agreement from sales of ourcommon stock we may elect to make to Roth Principal Investments pursuant to the Purchase Agreement after the date of this prospectus. See“The Committed Equity Facility” for a description of the Purchase Agreement and “Selling Stockholder” for additional information regardingRoth Principal Investments. Roth Principal Investments may sell or otherwise dispose of the common stock described in this prospectus in a number of differentways and at varying prices. See “Plan of Distribution (Conflict of Interest)” for more information about how Roth Principal Investments maysell or otherwise dispose of our common stock pursuant to this prospectus. Roth Principal Investments is an “underwriter” within the meaningof Section 2(a)(11) of the Securities Act of 1933, as amended, or the Securities Act. We will pay the expenses incurred in registering under the Securities Act the offer and sale of the shares of our common stock towhich this prospectus relates by the Selling Stockholder, including legal and accounting fees. We have also engaged Digital Offering, LLC(“Digital Offering”) to act as a “qualified independent underwriter” in this offering and have agreed to pay their fees for such services. See“Plan of Distribution (Conflict of Interest)” beginning on page 93. Our shares of our common stock are listed on The Nasdaq Capital Market under the symbol “FLUX.” On June 3, 2026, the lastreported sale price of our common stock on The Nasdaq Capital Market was $1.02 per share. Investing in our common stock involves a high degree of risk. You should review carefully the risks and uncertainties describedin the section entitled “Risk Factors” beginning on page 13 of this prospectus before buying our common stock. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense. The date of this prospectus is June 4, 2026. TABLE OF CONTENTS ABOUT THIS PROSPECTUS1MARKET AND INDUSTRY DATA1CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS1PROSPECTUS SUMMARY4THE OFFERING11RISK FACTORS13THE COMMITTED EQUITY FACILITY30USE OF PROCEEDS41MARKET INFORMATION FOR COMMON STOCK AND DIVIDEND POLICY42MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS43BUSINESS56MANAGEMENT72EXECUTIVE COMPENSATION78CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS83PRINCIPAL SECURITYHOLDERS85DESCRIPTION OF CAPITAL STOCK87SELLING STOCKHOLDER91PLAN OF DISTRIBUTION (CONFLICT OF INTEREST)93LEGAL MATTERS96EXPERTS96WHERE YOU CAN FIND MORE INFORMATION96INDEX TO CONSOLIDATED FINANCIAL STATEMENTSF-1 Neither we nor the Selling Stockholder have authorized anyone to provide you with information other than that contained in thisprospectus or any free writing prospectus prepared by or on behalf of us or to which we have referred you. We and the SellingStockholder take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may giveyou. The Selling Stockholder is offering to sell, and seeking offers to buy, the securities only in jurisdictions where offers and sales arepermitted. The information contained in this prospectus is accurate only as of the date on the front cover page of this prospectus, orother earlier date stated in this prospectus, regardless of the time of delivery of this prospectus or of any sale of our securities. No action is being taken in any jurisdiction outside the United States to permit a public offering of our securities or possession ordistribution of this prospectus in that jurisdiction. Persons who come into possession of this prospectus in jurisdictions outside theUnited States are required to inform themselves about and to observe any restrictions as to this offering and the distribution of thisprospectus applicable to that jurisdiction. ABOUT THIS PROSPECTUS Neither we nor the Selling Stockholder have authorized anyone to provide you with a