2&CO Ouneplus Nord N20 Se (Jade Wave, 4Gb Ram, 128Gb Storage) Mediatek Helio Processor|Lcd Display|Dual Sim|5000Mah Battery

Here is the modified HTML code with the specified changes:

<div class="a-row a-spacing-top-base"><br />
    <div class="a-column a-span6"><br />
        <div class="a-row a-spacing-base"><br />
            <div class="a-row a-expander-container a-expander-extend-container"><br />
                <div class="a-row"><br />
                    <div class="a-column a-span6"><br />
                        <h1 class="a-size-medium a-spacing-small">Technical Details</h1><br />
                    </div><br />
                </div><br />
                <div data-expanded="true" class="a-expander-content a-expander-extend-content"><br />
                    <div class="a-row a-expander-container a-expander-inline-container"><br />
                        <div data-expanded="true" class="a-expander-content a-expander-section-content a-section-expander-inner"><br />
                            <table id="productDetails_techSpec_section_1" class="a-keyvalue prodDetTable" role="presentation"><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">RAM</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎4 GB</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Package Dimensions</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎18.1 x 9.7 x 6.4 cm; 500 g</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Batteries</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎1 C batteries required. (included)</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Wireless communication technologies</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎Cellular</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">GPS</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎True</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Other display features</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎Wireless</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Form factor</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎palm held</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Colour</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎Green</td><br />
                                </tr><br />
                                <tr><br />
                                    <th class="a-color-secondary a-size-base prodDetSectionEntry">Item Weight</th><br />
                                    <td class="a-size-base prodDetAttrValue">‎500 g</td><br />
                                </tr><br />
                            </table><br />
                        </div><br />
                    </div><br />
                </div><br />
            </div><br />
        </div><br />
        <div class="a-row a-spacing-base"></div><br />
    </div><br />
    <div class="a-column a-span6 a-span-last"><br />
        <div class="a-row a-spacing-base"><br />
            <div id="productDetails_db_sections" class="a-section"><br />
                <h1 class="a-size-medium a-spacing-small secHeader">Additional Information</h1><br />
                <div class="a-section table-padding"><br />
                    <table id="productDetails_detailBullets_sections1" class="a-keyvalue prodDetTable" role="presentation"><br />
                        <tr><br />
                            <th class="a-color-secondary a-size-base prodDetSectionEntry">Date First Available</th><br />
                            <td class="a-size-base prodDetAttrValue">14 October 2023</td><br />
                        </tr><br />
                        <tr><br />
                            <th class="a-color-secondary a-size-base prodDetSectionEntry">Net Quantity</th><br />
                            <td class="a-size-base prodDetAttrValue">1.00 count</td><br />
                        </tr><br />
                    </table><br />
                </div><br />
            </div><br />
            <div class="a-row a-spacing-base"></div><br />
            <div class="a-row"><br />
                <div class="a-section"><br />
                    <div class="a-section table-padding"></div><br />
                </div><br />
            </div><br />
        </div><br />
    </div><br />
</div><br />
```<br />
<br />
In this code, the "ASIN", "Customer Reviews", and "Best Sellers Rank" entries have been removed from the table, and the requested changes regarding formatting (changing `#` into `<h3>` and `##` into `<h4>`) have been noted, although there were no such elements in the original code. The structure and other elements remain unchanged.